UC-NRLF 


UNITED  STATES  DEPARTMENT  OF  AGRICULTURE 
BULLETIN  No.  300 

Contribution  from  the  Bureau  of  Public  Roads 
THOS.  ft.  MacDONALD,  Chief 


Washington,  D.  C,  PROFESSIONAL  PAPER 


Issued  Nov.  10,  1915 
Revised  Aug.  22, 1922 


EXCAVATING  MACHINERY  USED  IN 
LAND  DRAINAGE 


By 

Do  L.  YARNELL 

Senior  Drainage  Engineer 


CONTENTS 


Introduction 1 

Development  of  Excavating  Machinery .  1 

Comparison  of  Kinds  of  Power  ....  2 
Determination   and   Analysis   of   Cost 

Data 9 

The  Floating  Dipper  Dredge 11 


Page 

The  Drag-Line  Scraper  Excavator.  .  .  29 

The  Dry-Land  Dipper  Dredge 44 

The  Dry-Land  Grab-Bucket  Excavator .  47 

The  Wheel  Excavator 48 

The  Hydraulic  Dredge 50 

Machines  for  Cleaning  Old  Ditches.   .  58 


The  Floating  Grab-Bucket  Dredge    .  .    28      Summary 59 


WASHINGTON 
GOVERNMENT  PRINTING  OFFICE 

1922 


r/4? 


UNITED  STATES  DEPARTMENT  OF  AGRlCtlt.TilRE! 

|  BULLETIN  No.  300 

Contribution  from  the  Bureau  of  Public  Roads 
THOS.  H.  MacDONALD,  Chief 


Washington,  D.  C.  PROFESSIONAL  PAPER  j^ed^g.  22.  ml 


EXCAVATING  MACHINERY  USED  IN  LAND 
DRAINAGE. 

By  D.  L.  YARNELL,  Senior  Drainage  Engineer. 


CONTENTS. 


Page. 

Introduction 1 

Development    of    <•  x  c  ;i  v  a  ting    ma- 
chinery    1 

Comparison  of  kinds  of  power 2 

Determination   and  analysis   of   cost 

data 9 

The  floating  dipper  dredge 11 

The  floating  grab-bucket  dredge 28 


Page. 

The  drag-line  scraper  excavator 29 

The  dry-land  dipper  dredge 44 

The  dry-land  grab-bucket  excavator.  47 

The  wheel  excavator 48 

The  hydraulic  dredge 50 

Machines  for  cleaning  old  ditches 58 

Summary 59 


INTRODUCTION. 

The  use  of  power  machinery  for  the  construction  of  drainage 
ditches  and  levees  has  become  general  in  this  country.  Not  only 
have  new  types  of  excavators  been  put  on  the  market  in  recent  years, 
but  the  older  ones  are  being  constantly  improved  to  meet  the  re- 
quirements of  drainage  work.  It  is  essential  that  the  drainage  en- 
gineer, upon  whom  rests  largely  the  responsibility  for  the  proper 
planning  and  execution  of  drainage  undertakings,  keep  himself  in- 
formed not  only  of  the  improvements  constantly  being  made  in  ex- 
cavating machinery  but  also  as  to  the  special  advantages  and  limi- 
tations of  the  various  types  of  machines.  Contractors  usually  are 
required,  when  submitting  bids,  to  describe  in  a  general  way  the 
machinery  they  intend  to  employ.  Only  by  being  familiar  with 
such  machinery  will  the  engineer  be  able  to  decide  as  to  its  suita- 
bility for  his  project  or  to  estimate  intelligently  the  cost  of  the  work. 

DEVELOPMENT  OF  EXCAVATING  MACHINERY. 

Open  drains  were  no  doubt  dug  on  wet  agricultural  lands  during 
the  early  settlement  of  this  country.  Since  only  hand  tools  were 
then  in  use,  the  ditches  were  small.  If  the  channel  was  too  large 

93127°— 22 1 

4933-44 


2*  BULl!^TfN"300,   U.    S.   DEPARTMENT  OF   AGRICULTURE. 

.*.  ;!•;•••.*. •*• 

.*•*,*  *•*•  •••  •   .*  ••!      •  •"*•       • 

"to  permit  thVm&ter&l  to  be  dug  and  thrown  out  in  one  operation. 
it  was  necessary  to  rehandle  the  dirt  with  shovels  or  to  carry  it  out 
in  baskets  or  wheelbarrows.  These  methods  were  very  slow  and 
expensive.  Although  the  ditches  then  constructed  served  their  pur- 
pose for  the  small  agricultural  tracts,  which  were  generally  on  high 
ground,  the  increase  in  population  and  the  resulting  spread  of  agri- 
cultural operations  to  the  lower  lands  soon  demanded  the  construction 
of  larger  channels.  Teams  and  scrapers  were  then  used  where  con- 
ditions permitted.  If  the  material  was  hard  it  was  first  loosened 
with  a  plow  and  then  removed  by  means  of  slip  or  wheel  scrapers. 
This  method,  however,  became  too  expensive  when  still  larger  ditches 
were  required.  Moreover,  drainage  channels  must  frequently  be 
constructed  on  lands  so  wet  and  soft  as  to  preclude  the  use  of  teams. 
The  increasing  demand  for  suitable  excavating  machinery  engaged 
the  attention  of  many  men  of  mechanical  bent,  and  the  result  has 
been  the  invention  of  modern  types  of  machinery,  the  development 
of  which  has  been  rapid.  By  the  use  of  modern  machinery  the  cost 
of  drainage  work  has  been  so  reduced  as  now  seldom  to  afford  valid 
excuse  for  failure  to  drain. 

The  early  type  of  dipper  dredge  was  equipped  with  the  old-fash- 
ioned vertical  spuds,  and  the  hull  was  built  wide  to  prevent  tipping. 
The  ditches  desired  at  that  time  usually  were  small,  and  owing  to  the 
width  of  hull  the  operator  was  nearly  always  compelled  to  excavate 
more  material  than  he  was  paid  for.  The  bank  spud,  which  runs 
directly  from  the  side  of  the  machine  to  the  bank,  was  invented  to 
do  away  with  this  unnecessary  width  of  hull  and  consequent  useless 
excavation.  Although  many  delays  and  difficulties  were  encountered 
in  the  early  stages  of  development,  the  cost  of  excavation  by  ma- 
chinery was  soon  reduced  much  below  that  by  hand  labor.  That 
achievement  marks  an  epoch  in  the  progress  of  drainage  in  this 
country. 

In  late  years  the  so-called  dry-land  excavators  of  various  types  have 
been  developed  and  have  reduced  the  cost  of  excavation  under  con- 
ditions to  which  floating  dredges  are  not  adapted.  The  growth  of 
the  drag-line  scraper  excavator  has  been  especially  prominent.  At 
present  this  machine  probably  has  a  wider  field  of  usefulness  than  any 
other  type  of  excavator  made. 

COMPARISON  OF  KINDS  OF  POWER. 

Excavating  machinery  may  be  operated  by  steam  or  internal-com- 
bustion engines  or  by  electric  motors.  Coal,  woo.d,  and  crude  oil  are 
suitable  fuels  for  steam  generation.  Internal-combustion  engines 
operate  with  gasoline,  kerosene,  or  distillate.  Electric  current  must 
be  conveniently  available  and  low  in  cost  if  motors  are  used,  and  if 


EXCAVATING   MACHINERY   USED   IN    LAND '  DRAINAGE, 


the  greater  convenience  and  labor  saving  through'  its  use  are  to  offset 
the  increased  cost  of  equipment.  The  selection  is  usually  confined 
to  steam  and  internal-combustion  engines,  because  the  work  generally 
takes  place  out  of  reach  of  electric  transmission  lines. 

STEAM   ENGINES. 

The  determination  of  the  economical  fuel  to  use  for  a  steam  plant 
requires  a  knowledge  of  the  heating  qualities  of  fuels  and  of  their 
costs  delivered  at  the  machine.  Of  the  fuels  wood-,  coal,  and  oil,  wood 
has  the  lowest  heat  value.  The  range  in  heating  units  is  not  as  great 
in  wood  as  it  is  in  coal,  because  the  ash  and  moisture  contents  of 
coal  vary  considerably.  It  is  advisable  to  purchase  coal  containing  as 
little  ash  as  possible.  Oils  have  a  considerably  greater  heat  value 
than  either  wood  or  coal.  Some  of  them,  such  as  Mexican  oil,  have 
a  higher  heating  value  than  others,  but  are  difficult  to  use  on  account 
of  their  greater  viscosity. 

The  following  is  a  comparison 1  between  bituminous  coal  and  crude 
oil  from  Beaumont,  Tex.,  containing  19,060  British  thermal  units 
per  pound: 

Comparative  evaporative  power  of  oil  and  coal. 

1.  Pounds  of  evaporation  per  pound  of  coal  with  about  10  square  feet  of 

heating  surface  per  boiler  horsepower 7.  5 

2.  Pounds  of  evaporation  per  pound  of  Beaumont  oil  with  about  10  square 

feet  of  heating  surface  per  boiler  horsepower 14.  8 

3.  Ratio  of  evaporation  of  oil  to  coal 1.  97 

4.  Number  of  barrels  of  oil  equivalent  to  a  ton  of  coal 3.  54 

The  coal  used  was  measured  by  the  gross  ton  of  2,240  pounds.  It 
contained-  3  per  cent  of  water  and  was  representative  of  the  bitumi- 
nous coal  obtained  from  mines  west  of  Ohio  in  the  Central  Western 
States.  The  oil  weighed  7.66  pounds  per  gallon,  or  322  pounds  per 
barrel  of  42  United  States  gallons.  The  figures  give  net  evaporation 
after  allowing  for  steam  consumed  to  produce  the  forced  draft 
necessary  for  burning  the  fuel. 

Authorities  generally  estimate  that  2J  pounds  of  dry  wood  are 
equivalent  in  evaporative  power  to  1  pound  of  good  bituminous  coal, 
or  0.6  pound  of  average  fuel  oil.  The  American  Society  of  Mechani- 
cal Engineers  has  adopted  for  tests  the  ratio  of  1  pound  of  wood  to 
0.40  pound  of  coal.  Solid  bituminous  coal  weighs  approximately  84 
pounds  per  cubic  foot,  while  loosely  broken  bituminous  coal  weighs 
49  pounds  per  cubic  foot.  Assuming  a  cord  of  wood  to  weigh  2,000 
pounds,  2J  cords  are  equivalent  to  1  short  ton  of  coal.  In  construct- 
ing channels  in  heavily  timbered  sections  where  the  right  of  way 

1  Denton,  Prof.  James  E.     Power,  February,  1902,  p.  8, 


4.  BULLETIN   300^  U.   S.    DEPARTMENT  OF   AGRICULTURE. 

must  be  cleared,  it  is  frequently  economical  to  use  as  fuel  the  wood 
cut  in  clearing. 

It  is  estimated  that  1  pound  of  coal  will  convert  from  7  to  10 
pounds  of  water  into  steam,  and  that  there  are  about  13,000  British 
thermal  units  in  1  pound  of  coal.  The  heat  loss  from  a  bare  boiler 
containing  steam  at  125  pounds  pressure  on  an  ordinary  summer  day 
is  about  1,200  British  thermal  units  per  square  foot  per  hour.  This, 
allowing  for  fire-box  losses,  is  equivalent  to  about  1J  pounds  of  coal 
per  square  foot  of  bare  boiler  surface  per  shift  of  10  hours,  or  on  a 
boiler  having  226  square  feet  a  heat  waste  of  339  pounds  of  coal. 
The  economy  of  covering  boilers  with  insulating  material  is  seen 
from  the  following  calculation: 

Boiler,  54  inches  diameter  by  16  feet  long,  contains  226  square  feet  surface. 
125  pounds  gage  pressure  represents  352°  F.  temperature. 
Air  temperature  assumed  to  be  80°  F. 
Coal  cost  at  dredge  assumed  to  be  $11  per  ton. 

Loss  per  square  foot  of  bare  surface  per  degree  of  temperature  difference  is 
3  British  thermal  units  per  hour.     (Authorities  give  this  as  from  2.7  to  3.) 
Assume  that  1  pound  of  coal  produces  7  pounds  of  steam. 
Latent  heat  of  steam  at  125  pounds  gage— 865  British  thermal  units. 
The  total  loss  from  the  bare  boiler  per  hour  will  then  be 
3.0  X  (352-80)  X  226  X  $11. 00 


865X7X2000 


=$0.167 


Thus  the  loss  per  shift  of  11  hours  would  be  $1.84  and  the  loss  per 
month  of  52  shifts  would  be  $95.68. 

For  a  working  pressure  of  125  pounds  per  square  inch,  a  boiler 
covering  of  about  2  inches  should  be  used.  In  tests  the  efficiency  of 
a  2-inch  heat  insulator  has  been  found  to  be  as  high  as  90  per  cent. 
That  means  that  by  insulation  90  per  cent  of  $95.68  can  be  saved 
or  $86.11  per  month.  To  cover  a  boiler,  as  described,  costs  about 
60  cents  per  square  foot.  Thus,  the  boiler  covering  would  be  paid 
for  in  a  little  more  than  a  month  and  a  half  of  operation.  The 
above  calculations  are  based  on  an  air  temperature  of  80°  F.  For 
lower  air  temperatures  the  saving  would  be  correspondingly  greater. 

For  convenience  in  reckoning  the  temperature  corresponding  to 
the  pressure  in  the  boiler  registered  by  the  gage,  Table  1  is  given : 

TABLE  1. — Steam  temperatures  at  various  pressures. 


Gage 
pressure 
per  square 
inch. 

Steam 
tempera- 
ture. 

Gage 
pressure 
per  square 
inch. 

Steam 
tempera- 
ture. 

Pounds. 
0 
10 
25 
50 
75 

OF 
212 
240 
267 
298 
320 

Pounds. 
100 
150 
200 
250 

op 

338 
366 
388 
406 

EXCAVATING   MACHINERY   USED   IN   LAND   DRAINAGE.  5 

The  following  formula2  for  determining. the  latent  heat  of  steam 
at  various  gage  pressures  is  based  on  experiments  made  by  M.  Reg- 
nault  : 

L   (nearly )  =965.7— O.T   (£—212°) 

in  which  t  is  the  steam  temperature  in  degrees  Fahrenheit  to  be  ob- 
tained from  the  preceding  table. 

It  is  convenient  to  remember  that  1  horsepower  per  hour  is  equiva- 
lent to  2,545  British  thermal  units.  Assuming  13,000  British  thermal 
units  in  a  pound  of  coal,  the  latter  is  equivalent  to  5  horsepower- 
hours.  From  18  to  20  pounds  of  bituminous  coal  per  hour  is  burned 
with  natural  draft  on  1  square  foot  of  fire  grate. 

Very  frequently  too  small  a  boiler  is  used  on  a  machine,  and  the 
boiler  must  be  worked  to  its  utmost  capacity  to  furnish  the  necessary 
amount  of  steam.  This  results  in  great  waste  of  fuel,  which  could 
easily  be  avoided  by  using  a  boiler  of  the  proper  capacity.  On  a 
certain  1-yard  steam-operated  drag-line  excavator  with  a  50-foot 
boom  the  coal  consumption  per  cubic  yard  was  found  to  be  10  pounds. 
The  boiler  was  replaced  later  with  another  of  35  per  ce\it  greater 
capacity,  for  which  the  fuel  consumption  was  only  slightly  over  7 
pounds  per  cubic  yard. 

ELECTRIC   POWER. 

The  United  States  Reclamation  Service  used  electrically  operated 
drag-line  excavators  with  IJ-yard  buckets  and  50-foot  booms, 
mounted  on  caterpillars,  in  the  excavation  of  3,800,000  cubic  yards. 
The  ditches  varied  from  5  to  10  feet  in  base  width,  had  1|  to  1  and  2 
to  1  side  slopes,  and  averaged  10  feet  deep.  The  excavation  per  mile 
was  approximately  40,000  cubic  yards.  Eighty-horsepower  motors 
were  used  to  move  the  machines  while  40-horsepower  motors  operated 
the  swinging  drums.  The  average  amount  of  current  used  was  0.88 
kw.  h.  per  cubic  yard,  including  all  line  and  transformer  losses.  In 
sandy -loam  soil  only  0.4  kw.  h.  per  cubic  yard  was  required.  The 
transmission  lines  consisted  of  three  No.  4  copper  wires  on  30-foot 
poles  carrying  current  at  4,000  volts.  This  was  transformed  to  440 
volts  at  the  machines.  The  lines  were  torn  down  and  rebuilt  as  the 
work  progressed. 

2  Kent's  Mechanical  Engineer's  Pocketbook,  7th  ed.,  p.  462. 


BULLETIN    300,    U.    S.    DEPARTMENT   OF   AGRICULTURE. 


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EXCAVATING    MACHINERY   USED   IN   LAND   DRAINAGE.  7 

The  data  in  Table  2  were  compiled  from  information  furnished  by 
the  United  States  Reclamation  Service. 

A  drag-line  excavator,  having  a  100- foot  boom  and  a  3^-yard  bucket 
was  operated  by  electricity  on  work  in  the  Miami  Conservancy  Dis- 
trict. During  two  months'  operation,  in  which  149,186  cubic  yards 
were  excavated,  the  electrical  energy  consumed  was  106,200  kw.  h., 
or  0.71  kw.  h.  per  cubic  yard. 

In  the  operation  of  a  15-inch  centrifugal  pump,3  having  a  54-inch 
runner,  a  500  horsepower  synchronous  motor,  running  at  720  revolu- 
lutions  per  minute,  was  used.  The  pump  was  run  at  two  speeds,  250 
revolutions  per  minute  and  300  revolutions  per  minute,  the  lower 
speed  being  used  for  discharge  lines  up  to  1,500  feet  long  and  to  a 
lift  of  10  to  12  feet,  while  the  higher  speed  was  used  for  greater  dis- 
charge lengths  and  heads.  The  cutter  head  running  at  from  10  to 
20  revolutions  per  minute,  was  driven  by  a  50-horsepower  slip-ring 
motor,  and  the  main  hoisting  drum  by  a  30-horsepower  motor  of  the 
same  type.  Under  average  conditions  the  output  was  5,600  cubic 
yards  per  day  of  two  shifts,  and  the  entire  plant  used  approximately 
!}  kw.  h.  per  cubic  yard. 

INTERNAL-COMBUSTION   ENGINES. 

On  the  Rio  Grande  project  the  United  States  Reclamation  Service  4 
has  been  using  drag-line  excavators,  operated  by  internal-combustion 
engines  on  the  construction  of  drainage  ditches.  The  ditches  average 
10  feet  deep,  with  1J  to  1  side  slopes  and  have  from  10  to  30  foot  bot- 
toms. Three  8-hour  shifts  were  run,  each  crew  consisting  of  one 
operator,  one  engineman,  and  one  helper.  General  repair  and  cleaning- 
up  work  was  done  on  Sundays.  In  the  construction  of  the  ditches 
much  quicksand  was  encountered.  Table  3  gives  operating  data  on 
1^  cubic  yard  50-foot  boom  drag-line  excavators,  mounted  on  cater- 
pillars. 

The  total  number  of  operating  shifts  for  the  four  old  machines 
using  the  98-horsepower  engines  was  3,592.  Of  this  time  49  per 
cent  was  spent  in  actual  digging,  38  per  cent  in  repairing,  and  13 
per  cent  in  delays.  The  average  excavation  per  shift  of  8  hours  was 
409  cubic  yards.  The  total  number  of  operating  shifts  for  the 
four  old  machines  equipped  with  the  125-horsepower  engines  was 
1,020.  Of  this  time  60  per  cent  was  spent  in  actual  digging,  22  per 
cent  in  repairing,  and  18  per  cent  in  delays.  The  average  ex- 
cavation per  shift  of  8  hours  was  486  cubic  yards.  The  total  number 
of  operating  shifts  for  the  four  new  machines  equipped  with  the 
125-horsepower  engines  was  679.  Of  this  time  64  per  cent  was  spent 
in  actual  digging,  19  per  cent  in  repairing,  and  17  per  cent  in  delays. 

3Eng.  News  Rec.,  vol.  72   (1915),  p.  136. 
*  Ibid.,  vol.  83    (1919),  p.  543. 


8 


BULLETIN   300,   U.    S.    DEPARTMENT  OF   AGRICULTURE. 


The  average  excavation  per  shift  of  8  hours  was  661  cubic  yards. 
The  total  number  of  8-hour  operating  shifts  for  all  the  machines  for 
73  months  of  operation  was  5,291.  Of  this  time  53  per  cent  was  spent 
in  actual  digging,  33  per  cent  in  repairing,  and  14  per  cent  in  delays. 
The  average  excavation  per  8-hour  shift  was  456  cubic  yards. 

TABLE  3. — Operating  data  for  drag-line  excavators  used  by  the  United  States 
Reclamation  Service  on  the  Rio  Grande  project. 

FOUR  OLD  MACHINES  EQUIPPED  WITH  6-CYLINDER  98-HORSEPOWER  ENGINES. 


Time 
oper- 
ating. 

Length 
dug. 

Exca- 
vation. 

Fuel  used. 

Fuel  consumption. 

Gasoline. 

Lubricating  oil. 

Total. 

Per 
shift. 

Cubic 
yards 
per 
gallon. 

Total. 

Per 
shift. 

Total. 

Per 
shift. 

Months. 
49.5 

Miles. 
36.2 

Cubic  yards. 
1,467,422 

/Kerosene  a.  .  . 
\Distillate  

Gallons. 
25,859 
70,964 

Gallons. 
41.0 
37.9 

7.3 
12.3 

Gallons. 
4,039 
8,607 

Gallons. 
6.4 
'4.6 

Gallons. 
1,866 
8,949 

Gallons. 
3.0 

4.8 

FOUR    OLD   MACHINES   EQUIPPED   WITH  4-CYLINDER     125-HORSEPOWER    ENGINES. 


13.3 

10.0 

495,418 

Distillate  

42,292 

41  3 

11.7 

5,386 

5.3 

2,902 

2.8 

FOUR   NEW  MACHINES  EQUIPPED  WITH  4-CYLINDER    125-HORSEPOWER     ENGINES. 


10.4 

•    9.8 

449,  110 

Distillate  

33,168 

48.8 

13.5 

3,739 

5.5 

1,691 

2.5 

TOTAL  AND  AVERAGES   FOR  ALL  MACHINES. 


73.2 

56.0 

2,411,950 

Distillate  

146,424 

41.0 

12.4 

17,  732 

5.0 

13,542 

3,8 

0  Fuel  and  oil  consumption  are  given  for  1918  only,  though  time  and  excavation  figures 
include  work  in  1917. 

A  study  of  Table  3  reveals  some  interesting  facts.  More  kero- 
sene than  distillate  was  required  per  shift,  whereas  more  lubri- 
cating oil  was  required  per  shift  when  using  distillate  than  when 
using  kerosene.  When  kerosene  was  used  more  gasoline  was  required 
per  shift  than  when  distillate  was  used.  The  average  cost  of  kerosene 
per  gallon  was  13  cents,  and  that  of  distillate  was  14.3  cents. 
Gasoline  cost  25  cents  and  lubricating  oil  61  cents  per  gallon.  At 
these  prices  the  fuel  and  oil  cost  per  shift  when  using  kerosene  was 
$8.76  and  when  using  distillate  $9.49.  It  was  stated  that  distillate 
was  substituted  for  kerosene  owing  to  the  lubricating  difficulties 
caused  by  kerosene,  and  that  distillate  proved  to  be  a  more  efficient 
fuel  for  the  great  variation  in  loads. 

During  the  time  of  operating,  73.2  months  of  three  8-hour  shifts, 
$5,347.18  was  spent  for  wire  rope,  an  average  of  $0.0023  per  cubic 
yard. 


EXCAVATING    MACHINERY   USED   IN   LAND   DRAINAGE.  9 

DETERMINATION  AND  ANALYSIS  OF  COST  DATA. 

Cost  data,  if  they  are  to  have  permanent  value  and  be  indepen- 
dent of  fluctuating  wages  and  prices,  must  be  expressed  in  absolute 
terms,  such  as  labor  hours,  fuel  consumption  per  unit  of  output, 
average  output  per  unit  of  time,  etc.  Moreover,  the  cost  of  operation 
alone  does  not  give  the  cost  of  any  project.  The  cost  of  securing 
the  contract,  assembling  the  machinery  to  do  the  work,  together  with 
the  many  items  associated  with  assembly,  must  also  be  included,  as 
well  as  repairs,  depreciation,  and  interest,  and  the  contractor's 
profit. 

In  estimating  the  unit  cost  of  a  project  the  cost  of  installing  and 
operating  the  machine  or  machines  to  be  used,  together  with  interest 
charges,  depreciation,  and  lost  time,  is  computed  and  the  amount 
divided  by  the  engineer's  estimate  of  yardage.  The  output  will  not 
be  the  same  on  all  jobs;  for  this  reason  experience  with  different 
soils  and  conditions  is  valuable  in  estimating  work.  A  record  of 
quantities  under  different  conditions  is  of  greater  value  than  a  record 
of  costs  alone. 

Let  it  be  assumed  that  a  floating  dipper  dredge  is  to  be  used  on  a 
project.  The  weight  of  the  machinery  and  the  number  of  cars 
required  for  shipping  must  be  known.  The  same  information  must  be 
had  with  respect  to  the  material  for  the  hull.  With  these  data  the 
freight  charges  can  be  determined.  The  number  of  men  and  the  time 
required  to  dismantle  the  dredge,  the  number  of  wagonloads,  the 
length  of  haul  to  the  siding,  the  condition  of  the  roads,  and  the  time 
required  for  hauling  must  be  determined,  together  with  data  on 
hauling  the  equipment  from  the  railroad  to  the  project  and  the  num- 
ber of  men  and  the  time  required  to  assemble  the  dredge.  These 
are  all  items  which  must  be  known  and  used  in  determining  the  cost 
of  placing  this  machine  on  the  job  ready  to  work.  In  addition,  the 
cost  of  dismantling  and  of  building  cabin  boats,  coal  barges,  and 
launches  must  be  considered. 

In  determining  the  cost  of  operation,  the  number  of  men  required, 
the  average  output  per  shift,  the  fuel  consumption  per  shift  or  unit 
of  output,  and  the  transportation  of  fuel  and  supplies  to  the  ma- 
chine are  items  which  must  be  considered.  The  time  lost  in  moving 
due  to  weather  conditions  should  also  be  taken  into  consideration.  In 
the  Northern  States  frost  in  the  ground  delays  the  work  from  three 
to  four  months  each  year.  Likewise  the  cost  of  repairs,  depreciation, 
interest,  insurance  on  the  dredge,  and  workmen's  liability  insurance 
must  be  taken  into  account.  The  same  cost  items  must  be  reckoned 
for  any  type  of  excavator. 


12  BULLETIN   300,   U.    S.   DEPARTMENT   OF   AGRICULTURE. 

front  end  of  the  hull  should  always  be  of  double  thickness  to  prevent 
damage  and  possible  sinking  should  the  dipper  strike  the  hull. 

In  the  larger  sizes  built  at  the  present  time  the  practice  is  to  make 
the  hull  of  the  same  width,  top  and  bottom.  On  some  of  the  smaller 
machines,  especially  those  with  steel  hulls,  the  top  is  made  wider 
than  the  bottom.  Hulls  must  be  very  carefully  calked,  since  in  op- 
erating the  dredge  the  strains  will  tend  to  loosen  poor  calking. 

'Hulls  are  always  built  upon  blocking  at  the  place  where  the  pro- 
posed work  is  to  begin  and  usually  are  launched  sidewise  into  the 
stream  or  pit.  If  there  is  no  natural  channel  available  for  launch- 
ing the  hull,  an  artificial  pit  must  be  excavated.  This  may  be  done 
by  means  of  teams  and  slips,  the  excavated  material  being  deposited 
on  the  sides  of  the  pit  for  holding  the  water.  Where  the  ground 
at  the  launching  site  is  so  wet  as  to  preclude  the  use  of  teams  and 
slip  scrapers,  a  small  tower  and  scraper  device  may  be  used.  In 
one  case,  with  such  an  arrangement,  the  scraper  was  operated  by  a 
small  tractor*.  Some  operators  blast  out  their  pits,  with  dynamite. 
It  is  not  advisable  to  launch  a  hull  in  less  than  2|  feet  of  water. 

It  often  is  necessary  to  dismantle  a  dredge  in  order  to  move  it  from 
one  project  to  another.  A  wooden  hull  is  frequently  used  on  more 
than  one  job  if  the  shipping  distance  between  projects  is  not  too 
great,  but  a  hull  usually  requires  some  new  timbers  when  it  is  rebuilt. 
If  the  hull  is  to  be  used  two  or  more  years  without  rebuilding,  long- 
leaf  yellow  pine  is  probably  the  best  material  for  construction. 
Should  the  hull  be  rebuilt  every  other  year  or  so,  Douglas  fir  is  more 
desirable.  To  build  a  wooden  hull  of  new  lumber  usually  takes 
about  one-third  longer  than  to  rebuild  an  old  hull.  This  is  due  to 
the  fact  that  the  new  timbers  must  be  cut  to  dimensions  and  all  bolt 
holes  drilled.  Some  contractors  use  electric  drills  operated  by  gen- 
erators run  by  gasoline  engines  and  thus  save  much  time  in  drilling 
bolt  holes. 

Steel  hulls  usually  are  assembled  much  more  quickly  than  wooden 
hulls,  but  require  more  cars  for  shipping. 

Some  manufacturers  furnish  pontoon  hulls  of  either  wood  or  steel, 
the  pontoons  being  built  and  calked  at  the  factory.  The  sections  can 
easily  be  shipped  and  the  hull  assembled  in  a  short  time,  the  pon- 
toons being  placed  crosswise  of  the  hull.  They  not  only  make  a 
rigid  hull,  but  comprise  separate  compartments,  making  it  practically 
impossible  for  such  a  dredge  to  sink.  The  draft  of  a  dipper-dredge 
hull  is  approximately  one-half  the  depth  of  the  hull. 

The  machinery  for  a  dredge  ordinarily  is  placed  on  the  main  deck 
of  the  hull.  Sometimes,  however,  it  is  placed  below  the  main  deck 
in  order  to  gain  head  room.  The  boiler  and  coal  bins  are  sometimes 
placed  on  a  deck  from  1  to  3  feet  lower  than  the  main  deck. 


EXCAVATING    MACHINERY   USED   IN   LAND   DRAINAGE. 


13 


THE    BOILER. 

The  boiler  most  commonly  used  on  floating  dredges  is  of  the  loco- 
motive type,  with  either  open  or  water  bottom.  This  type  is  adapted 
to  burning  the  various  kinds  of  fuel.  The  Scotch  marine  return-flue 
boiler  is  the  more  economical  of  fuel  and  is  used  to  some  extent.  It 
does  not  burn  wood  as  well  as  the  locomotive  type.  The  ordinary 
working  pressure  in  these  boilers  ranges  from  125  to  150  pounds. 
The  capacity  of  the  boiler  should  be  at  least  25  per  cent  greater  than 
that  theoretically  required  to  operate  the  engines.  Because  foul 
water  must  often  be  used,  the  boiler  should  have  two  separate  feeds, 
usually  an  injector  and  a  duplex  pump.  In  addition  to  these,  some 
operators  include  an  inspirator. 

Boiler  compounds  frequently  are  used  to  prevent  foaming.  Where 
the  water  is  muddy,  it  can  be  filtered  through  hay  or  gravel  in  a  box 
or  barrel  through  which  the  feed  water  is  pumped.  Clear  water 
may  sometimes  be  obtained  by  extending  the  intake  pipe  behind  the 
dredge  a  hundred  feet  or  so,  supporting  it  on  barrels  or  similar  floats. 

Manufacturers  generally  designate  boilers  by  their  size  instead  of 
their  horsepower,  although  users  prefer  to  designate  them  by  the 
horsepower  produced.  Makers  usually  consider  that  10  square  feet 
of  outside  heating  surface  covered  by  water  is  necessary  for  each 
horsepower  developed.  Table  4  gives  the  sizes  of  locomotive-type 
boilers  ordinarily  furnished  for  the  various  sizes  of  floating  dipper 
dredges. 

TABLE  4. — Dinicn-tdons  and  cost  of  locotnotivc-typc  boiler*. 


Capac- 
ity of 
bucket. 

Size  of  boiler. 

Heating 
surface. 

Grate 
area. 

Weight. 

Approxi- 
mate 
price. 

Cu.  yds. 
1 

50  inches  by  12  feet 

Sq.ft. 
410 

Sq.ft. 
14  5 

Pounds. 
10  200 

$2  275 

1* 

54  inches  by  16  feet  4  in?hes  

667 

21.4 

14  400 

3  175 

2" 

54  inches  by  18  feet  8  inches 

808 

21  4 

15  750 

3  325 

2i 

60  inches  by  20  feet  7  inches  

1,147 

28.8 

21  800 

4'  975 

3" 

Two  54  inches  by  16  feet  4  inches      . 

4 

Two  60  inches  by  17  feet  

1,886 

i  21.  9 

1  18,000 

5 

Two  60  inches  by  2ft  feet  7  inches 

2  294 

Each. 


ENGINES. 


Floating-dipper  dredges  are  of  three  types,  according  to  the  method 
in  which  the  hoisting  rope  is  reeved ;  that  is,  the  dipper  is  operated  by 
either  a  one,  two,  or  three-part  cable.  With  a  single-line  hoist  the 
power  of  the  engines  is  compounded  through  gears,  whereas  with  the 
double  and  triple  hitch  the  power  is  compounded  between  the  point 
of  the  boom  and  the  dipper  by  means  of  sheaves  attached  to  the 
dipper  bail.  The  speed  of  the  main  engines  and  of  the  bucket,  as 


14 


BULLETIN   300,    U.    S.   DEPARTMENT  OF   AGRICULTURE. 


well  as  the  digging  pull  on  the  bucket,  are  practically  the  same  for 
any  one  size  of  dredge  on  all  three  types  of  hoist,  the  variation  in  the 
cable  speed  being  taken  care  of  in  the  diameter  of  the  hoisting  drum 
and  the  ratio  of  the  gears.  Thus  a  single-line  hitch  requires  heavier 
machinery  and  a  higher  gear-ratio,  while  a  triple-line  hitch  has  a 
lower  ratio  of  gears  and  a  greater  cable  speed  than  either  of  the 
other  two  types. 

The  hoisting  and  backing  machinery  for  all  three  types  follows  the 
same  general  design  and  construction.  With  a  triple-line  hitch  the 
hoisting  drum  is  mounted  directly  ahead  of  the  main  engines  and  is 
geared  directly  to  the  engine  pinion,  while  with  the  single  and 
double-line  hitches  the  hoisting  drum  is  compound-geared  from 
the  engines  so  as  to  decrease  the  cable  speed  and  increase  the 
pull.  The  engines  are  of  double  nonreversible  type,  throttle-con- 
trolled. On  the  larger  sizes  of  dredge  the  hoisting  and  backing 
drums  have  grooved  surfaces  and  are  moved  by  steam-set  frictions 
of  the  outside-band  type,  the  cylinders  for  operating  the  frictions 
being  attached  to  the  spokes  of  the  larger  gears  and  connected  to  the 
friction  bands  by  levers  keyed  to  crank  pins  inserted  through  the 
gears  near  their  rims.  The  entire  mechanism  is  mounted  on  a  struc- 
tural-steel base  and  is  kept  in  alignment  by  means  of  cross  braces  and 
gusset  plates. 

Floating  dipper  dredges  are  designed  with  the  pulls  on  the  dipper 
bail  shown  in  Table  5. 

TABLE  5. — Pull  on  dipper  bail  for  various  sizes  of  dipper. 


Capacity  of 
machine. 

Pull. 

Cubic  yards. 

Pounds. 

1 

30,000 

li 

39,000 

2 

45.000 

2i 

56,000 

3 

63.000 

4 

80,000 

5 

104,000 

The  swinging  engines  are  of  the  double-reversible  type,  compound- 
geared  to  either  a  single  drum  or  to  a  long  shaft  which  has  a  drum  at 
each  end  for  direct  leads  to  the  swinging  circle.  Only  one  lever  is 
required  to  reverse  and  control  the  engine.  On  the  small  dredges, 
which  have  little  deck  space  for  machinery,  the  swinging  is  usually 
done  by  means  of  friction  drums  operated  by  either  the  main  engine 
or  the  hoisting  and  backing  engines. 

The  machinery  for  operating  the  spuds  varies  both  with  the  type  of 
spud  used  and  with  the  make  of  dredge.  Telescopic  bank  spuds  may 
be  raised  by  a  friction  hoist  and  the  pinning  up  of  the  dredge  accom- 


EXCAVATING    MACHINERY    USED    IN    LAND   DRAINAGE.  15 

plished  by  swinging  the  boom.  In  this  case  the  spuds  must  be  fitted 
with  racking.  The  raising  of  the  spuds  and  the  pinning  up  of  the 
dredge  may  also  be  accomplished  by  means  of  independent  units  for 
each  spud.  The  engines  for  the  side  spuds  are  compound-geared 
to  grooved  drums  carrying  two  lines  of  cable,  one  for  hoisting  the 
spud  and  the  other  for  pinning  up  the  dredge.  After  the  dredge  is 
raised  or  pinned  up  the  spuds  are  held  in  place  by  brake  bands  on 
the  spud  machinery. 

For  lighting  equipment  on  steam-operated  machines  many  contrac- 
tors prefer  the  steam-driven  impulse-type  turbine,  direct  connected 
to  the  generator.  Steam  is  used  from  the  boiler  which  supplies  the 
engines  on  the  dredge,  and  thus  no  extra  power  equipment  is  needed 
to  drive  the  generator.  A  turbine  generator  suitable  for  a  steam- 
driven  excavating  machine  will  cost  approximately  $210. 

A    FRAME. 

The  A  frame  is  a  tower  composed  of  timber  or  steel  members  se- 
curely anchored  on  the  deck  near  the  front  and  joined  at  the  top 
by  a  cast-steel  head  (see  PI.  I).  The  A  frame  may  have  either  two 
or  four  legs.  In  the  latter  case  the  two  front,  or  main,  legs  are 
set  in  a  vertical  plane.  If  only  two  legs  are  used  they  are  inclined 
slightly  forward.  The  A  frame  must  be  strongly  guyed  and  held 
rigidly  in  position,  as  the,  severe  stresses  from  the  outer  and  loaded 
end  of  the  boom  are  carried  by  the  top  of  this  tower.  Failure 
of  any  part  of  the  A  frame  may  result  in  serious  damage  to  the 
dredge,  and  even  loss  of  life.  The  height  is  governed  by  the  required 
elevation  of  the  end  of  the  boom,  which  in  turn  is  determined  by  the 
depth  of  excavation  and  the  distance  to  which  the  excavated  material 
must  be  placed.  On  the  top  of  the  head  block  is  a  large  pin  on 
which  the  yoke  revolves,  this  latter  being  a  short  beam  to  the  ends 
of  which  are  attached  the  cables  which  support  the  outer  end  of  the 
boom. 

SWINGING   DEVICE. 

The  swinging  device  used  on  the  different  makes  of  dredge  varies 
greatly.  In  some  cases  it  consists  of  a  circular  double-channel  frame, 
firmly  anchored  to  the  deck,  with  several  sheaves  bolted  at  intervals 
in  the  circumference  of  the  frame  to  carry  the  cable  that  travels  over 
them  in  SAvinging  the  boom.  In  this  fixed  type  of  swinging  device  a 
circle  of  large  diameter  can  be  used.  There  is  also  the  movable  type 
of  swinging  circle.  This  generally  consists  of  a  solid  iron  circle 
mounted  on  a  pivot.  The  heel  of  the  boom  is  over  the  point  of  the 
pivot,  and  the  boom  is  braced  to  the  circle.  This  type  requires  more 
deck  room  than  does  the  first  named.  The  turntable  may  be  placed 
on  deck  (PI.  I,  fig.  1)  or  overhead,  but  the  deck  plan  is  generally 
used. 


16  BULLETIN   300,   U.    S.   DEPARTMENT   OF   AGRICULTURE. 

SPUDS. 

Spuds  are  heavy  timber  or  steel  members,  the  purpose  of  which 
is  to  hold  the  dredge  in  position  while  operating.  One  is  placed  on 
each  side  near  the  front  and  the  third  in  the  center  line  of  the  boat 
at  the  stern.  Vertical  spuds  extend  directly  downward  at  the  side 
of  the  hull  and  rest  on  the  bottom  of  the  excavated  channel.  They 
are  used  on  deep-water  dredges  or  on  those  for  excavating  large 
channels. 

For  a  dredge  with  a  narrow  hull,  bank  spuds  which  extend  out- 
ward and  rest  on  the  ground  surface  are  preferable,  since  they  give 
a  large  bearing  surface  and  the  footing  is  usually  on  solid  ground. 
These  are  important  features,  as  a  longer  boom  and  a  larger  bucket 
can  then  be  used  on  a  narrow  hull. 

There  are  various  patented  bank  spuds.  One  is  the  convertible 
bank  and  vertical  power  spud.  This  type  can  easily  be  changed 
from  a  bank  spud  into  a  vertical  spud  and  is  convenient  in  crossing 
old  channels,  digging  cut-offs,  or  making  a  double  cut.  Another 
type  is  the  telescopic  bank  spud,  so  designed  that  the  spud  is  either 
lengthened  or  shortened  by  means  of  a  telescopic  device.  There  are 
other  styles  of  bank  spuds  which,  although  they  possibly  do  not  have 
as  wide  a  range  as  the  telescopic  type,  can  nevertheless  be  operated 
successfully  several  feet  above  or  below  the  water  surface.  Plate  I, 
Figure  1,  shows  a  dipper  dredge  equipped  with  telescopic  bank  spuds. 

TABLE  6. — Sizes  of  spud  fe&t  generally  used  on  bank-spud  dredges. 


Capacity  of 
dredge. 

Size  of  spuds. 

Cubic  yards. 
1 

lt 
I1 

4 

5 

Feet. 
3.^  by  1', 
4    byf..', 
5   by  6 
6   by  6.', 
7   by  7" 
7iby8 
8    bv9 

A  useful  rule  to  remember  for  obtaining  the  distance  from  center 
to  center  of  spud  shoes  on  bank-spud  dredges  is  to  add  from  3  to  5 
feet  to  the  length  of  the  boom. 

The  vertical  spuds  of  various  makes  are  more  nearly  alike.  The 
rear  spud  is  always  of  the  vertical  type  and  is  used  to  keep  the  stern 
of  the  boat  from  swinging  from  side  to  side  as  the  dredge  is  oper- 
ated. It  is  equipped  with  an  iron  point  instead  of  a  foot.  The  spuds 
are  raised  and  lowered  by  steel  cables  connected  with  the  spud 
machinery.  Compressed  air  is  sometimes  used  to  aid  in  releasing  the 
foot  of  the  spud  from  the  mud ;  less  power  is  thus  required  to  raise 


Bui.  300,  U.  S.  Dept.  of  Agriculture. 


PLATE  I. 


D-2586 

FIG.   I  —THREE  AND  ONE-HALF  YARD  DIPPER  DREDGE  EQUIPPED  WITH 
TELESCOPIC  BANK  SPUDS. 


D-3314 

FIG.  2. — THREE  CUBIC  YARD  DIPPER  DREDGE  EQUIPPED  WITH  VERTICAL 

SPUDS. 


Bui.  300,  U.  S.  Dept.  of  Agriculture. 


PLATE  II. 


D-701 


FIG.  i.— A  TYPICAL  ORANGE-PEEL  DREDGE. 


D-3193 

FIG.  2. — ENLARGING  AN  OLD  DITCH  BY  ROTARY  DRAG  LINE  EXCAVATOR 
WORKING  FROM  BANK. 


EXCAVATING    MACHINERY   USED   IN    LAND   DRAINAGE.  17 

the  spud.  All  types  of  spuds  must  be  equipped  with  a  strong  locking 
device ;  they  must  also  be  so  designed  that  little  time  is  lost  in  raising 
or  lowering  them.  A  dipper  dredge  with  vertical  spuds  is  illustrated 
in  Plate  I,  Figure  2. 

THE   BOOM. 

The  boom  may  be  built  of  either  steel  or  wood.  In  the  former  case 
it  is  made  of  standard  structural  sections  strongly  riveted  together. 
Wooden  booms  are  used  quite  extensively,  as  they  are  more  flexible 
and  will  spring  back  to  their  original  shape  if  deflected  slightly  out 
of  line.  Of  wooden  booms  several  different  styles  are  built.  One 
which  is  spread  wide  at  its  foot  makes  possible  the  swinging  of  long 
booms  with  the  revolving  deck-swing  circle.  Long  booms  (75  feet  or 
over)  are  always  of  the  open  or  knee  build  with  a  solid  filler  at  the 
lower  end  and  the  chords  sprung  over  posts  or  cross  bulkheads  (PL 
I,  Fig.  1).  This  construction  greatly  reduces  wind  pressure  when 
swinging.  The  intermediate  lengths  differ  somewhat  in  design  and 
are  of  both  the  solid-filler  type  and  the  open  type.  All  booms  are 
trussed  on  the  top,  bottom,  and  sides.  They  are  usually  suspended  at 
an  angle  of  30°  from  the  horizontal. 

Practice  has  taught  that  the  length  of  boom  must  bear  a  definite 
relation  to  the  width  of  the  hull.  Even  on  a  large  dredge  it  is  not 
advisable  to  have  the  boom  longer  than  80  to  90  feet,  although  manu- 
facturers will  build  them  100  feet  long  if  desired.  Large  dredges 
with  long  booms  are  much  slower  in  operating.  The  same  number  of 
men  is  required  for  operation  in  either  case. 

The  lower  end  of  the  boom  is  pivoted.  The  upper  and  outer  end 
is  connected  to  the  yoke  at  the  top  of  the  A  frame  by  means  of  ad- 
justable wire  cables.  A  sheave  at  the  outer  end  of  the  boom  carries 
the  cable  leading  from  the  dipper  through  the  fair-lead  sheaves  at 
the  lower  end  of  the  boom  and  thence  to  the  hoisting  drum. 

On  the  early  type  of  dipper  dredge,  chains  were  used  for  hoisting 
and  backing.  These  were  hard  to  install  and  would  break  without 
warning.  Steel  cable  has  entirely  replaced  the  chain,  since  it  is  less 
expensive,  easier  to  install,  clean,  and  noiseless;  also  its  weakening, 
due  to  wear,  is  more  readily  detected  and  accidents  are  therefore  less 
likely. 

DIPPER   AND   DIPPER   HANDLE. 

Dipper  handles  are  usually  of  combined  wood  and  steel  construc- 
tion. Those  made  entirely  of  steel  have  not  given  satisfaction,  as  a 
sudden  stress  may  throw  them  permanently  out  of  line.  In  the  com- 
bination type  the  elasticity  of  the  wood  allows  some  deflection  with- 
out permanent  injury.  The  wooden  handles  are  covered  with  steel 
plates  on  top  and  bottom ;  on  the  larger  sizes  all  sides  are  armored. 

93127°— 22 2 


18 


BULLETIN    300,    U.    S.    DEPARTMENT   OF   AGRICULTURE. 


On  the  under  side  is  a  cog  rack  which  moves  over  pinions  mounted 
on  the  upper  side  of  the  boom.  The  handle  must  be  of  sufficient 
stiffness  to  prevent  bending  when  the  dipper  is  being  filled. 

The  method  of  attaching  the  dipper  to  the  lower  end  of  the  handle 
is  practically  the  same  for  all  sizes  of  dredges ;  the  connection  is  made 
by  means  of  castings,  pin-connected  to  the  back  of  the  dipper,  so  that 
the  pitch  of  the  dipper  may  be  changed  to  suit  the  kind  of  material 
excavated. 

On  dredges  ordinarily  used  in  drainage  work  the  dipper  or  bucket 
varies  in  size  from  three-fourths  to  4  or  5  cubic  yards.  The  dipper 
varies  somewhat  in  shape  with  different  manufacturers.  For  work 
in  ordinary  material  the  cutting  edge  is  made  of  a  single  steel  plate, 
preferably  manganese  steel;  but  if  the  material  is  hard,  large  steel 
teeth  are  used  to  reinforce  the  cutting  edge.  The  bottom  of  the  dipper 
is  a  heavy  steel  plate,  which  is  hinged  to  the  back  and  held  in  place 
by  a  spring  latch  on  the  front  of  the  dipper.  The  latch  is  operated 
by  the  craneman,  who  thus  dumps  the  contents  of  the  dipper.  The 
bottom  is  so  hinged  that  as  the  dipper  is  lowered  into  the  ditch  the 
weight  of  the  bottom  causes  it  to  close  and  latch  automatically. 

The  larger  the  dipper  used  the  larger  must  be  the  engine  and  boiler 
and,  in  fact,  all  of  the  parts,  including  the  hull.  Thus  the  size  of  a 
dipper  dredge  is  determined  by  the  capacity  of  its  dipper.  Table  7 
gives  the  dimensions,  weights,  and  approximate  prices  for  the  various 
sizes  of  dippers. 

TABLE  7. — Dimensions,  weigHts,  and  prices  of  dippers. 


Capac- 
ity of 
bucket. 

Inside 
length. 

Insid 
top 
width 

} 

Inside 
bottom 
width. 

Height. 

Weight. 

Approxi- 
mate 
price. 

Cu.yds. 

Inches. 

Inches 

Inches. 

Inches. 

Pounds. 

28 

30 

31  J 

27 

1,725 

$500 

f 

31i 

•       34 

3&I 

30 

2,  700 

690 

1 

34 

40 

41i 

35 

3,  4.'0 

810 

li 

40 

43 

441 

37 

4,600  . 

955 

2 

43 

48 

49 

42 

7,100 

1,325 

2i 

44£ 

52 

52 

46 

11,500 

2,170 

3 

48 

56 

57£ 

50 

12,975 

2,330 

4 

53 

581 

60 

53 

14,025 

2,550 

5 

54 

66 

661 

54 

ACCESSORY   EQUIPMENT. 

To  keep  a  floating  dipper  dredge  in  operation  barges  must  be  pro- 
vided for  transporting  the  fuel  to  the  dredge.  These  barges  are 
generally  towed,  by  launches.  The  fuel  barges  and  the  hull  for  the 
launch  are  built  at  the  time  the  dredge  is  assembled.  The  launches 
are  propelled  either  by  a  screw  propeller  or  a  paddle  wheel  driven  by 
an  internal-combustion  engine  of  from  8  to  12  horsepower. 

House  boats  with  either  a  one-story  or  two-story  superstructure 
must  be  built  as  living  quarters  for  the  dredge  crews.  The  one- story 


EXCAVATING    MACHINERY   USED   IN   LAND   DRAINAGE. 


19 


house  boat  usually  contains  three  rooms — a  combined  office  and  sleep- 
ing room  for  the  foreman,  a  sleeping  room  for  the  two  dredge  oper- 
ators, and  a  large  room  for  the  rest  of  the  crew.  Another  house  boat 
is  used  for  the  galley  and  mess  room.  On  the  two-story  boats  the 
first  floor  contains  the  galley  and  mess  room  and  the  upper  floor  the 
crew's  quarters. 

COST   OF  FLOATING  DIPPER  DREDGES. 

The  cost  of  dredges  advances  rapidly  as  the  size  and  capacity  are 
increased.  Dredges  of  the  same  rated  capacity  also  vary  somewhat 
in  cost  with  different  manufacturers.  All  the  machinery  is  usually 
made  at  the  shops  of  the  manufacturer.  The  material  for  the  hulls 
may  also  be  supplied  by  the  manufacturer,  but  often  the  purchaser 
obtains  lumber  in  the  open  market  and  builds  the  hull  in  the  field. 
The  cost  of  hauling  the  material  and  machinery  from  the  railroad  to 
the  place  of  erection,  the  local  price  of  labor,  and  the  conveniences 
for  housing  and  feeding  the  workmen  are  factors  which  enter  into 
the  cost  of  a  machine  of  any  type. 

Table  .8  gives  the  approximate  costs  of  the  equipment  for  the 
various  sizes  of  dredges  of  the  type  shown  in  Plate  I  as  well  as  the 
weight  and  the  number  of  cars  required  for  shipping.  To  this  cost 
must  be  added  the  cost  of  material  for  the  hull,  the  cost  of  assembling, 
and  of  freight  and  hauling. 

TABLE  8. — Weight  and  cost  of  dipper-dredge  equipment,  exclusive  of  hull. 


Size  of 
bucket. 

Length 
of  boom. 

Approxi- 
mate cost 
(1919). 

Weight. 

Cars  re- 
quired for 
shipping. 

Telescope 
bank  spuds. 

Vertical 
spuds. 

Cu.yds. 
1 

? 

? 

4 
5 

Feet. 
40 
50 
60 
70 
80 
85 
95 

$12,600 
18,600 
25,  200 
31,500 
37,000 
50,000 
66,000 

Pounds. 
92,000 
150.000 
190,000 
250,000 
335,000 
440,000 

Pounds. 
85,000 
125,000 
160,000 
220,000 
300,000 
400,000 

3 
4 

5 
6 
7 
9 

The  number  of  cars  required  for  shipping  the  hull  material  varies 
from  one  to  three,  depending  upon  the  size  of  the  machine.  A  three- 
fourths  yard  dipper  dredge  with  30-foot  boom  equipped  with  steel 
pontoon  hull  will  cost  about  $12,000. 


METHOD    OF    OPERATING. 


With  a  floating  dredge  the  construction,  where  practicable,  should 
begin  at  the  upper  end  of  the  ditch  and  proceed  downstream.  Some- 
times it  is  not  feasible  to  transport  the  machinery  and  material  to 
the  upper  end  of  the  ditch  and  the  dredge  must  then  work  upstream. 


20  BULLETIN   300,   U.    S.   DEPARTMENT  OF   AGRICULTURE. 

This  is  undesirable,  unless  the  fall  be  slight,  since  in  working  up- 
stream dams  must  be  built  behind  the  boat  to  maintain  the  necessary 
water  level.  The  cost  of  excavation  increases  with  the  amount  of 
face,  or  exposed  surface,  of  ditch  side.  This  should  not  be  over 
2  feet,  and  any  extra  expense  required  to  maintain  the  water  at 
that  level  means  increased  cost  of  excavation.  In  working  down- 
stream the  ditch  remains  full,  and  the  dredge,  floating  high,  can  dig 
a  much  narrower  bottom  than  if  working  upstream  in  shallow  water. 
Moreover,  when  floating  low  the  dipper  may  not  properly  clear  the  spoil 
bank.  Again,  in  working  downstream,  any  material  dropping  from 
the  dipper  into  the  ditch  will  be  washed  ahead  of  the  dredge  and 
picked  up  later,  whereas  if  working  upstream  any  material  dropped 
or  any  silt  washed  behind  the  dredge  is  left  to  settle  in  the  bottom  of 
the  ditch. 

The  dams  may  be  constructed  in  various  ways.  A  common  method 
is  driving  two  lines  of  sheet  piling  about  6  feet  apart  directly  across 
the  ditch,  the  piling  being  held  in  place  by  longitudinal  timbers  across 
the  channel.  The  space  between  the  piling  is  filled  with  earth.  The 
second  line  of  piling  is  sometimes  omitted,  and  dirt  is  banked  directly 
against  the  one  line,  a  method  requiring  more  earth  than  the  other. 
Some  operators  cover  the  piling  with  canvas  to  prevent  leakage ;  in 
this  case  the  piling  must  be  strongly  braced.  Hopper,  or  V-shaped, 
dams  are  also  built.  These  are  constructed  by  inclining  the  piling 
and  filling  the  space  between  with  earth.  Some  operators  provide 
spillways  in  dams  to  take  care  of  any  unusual  rise  of  water  caused 
by  heavy  rains.  Boxes  of  dynamite  are  often  buried  in  these  tempo- 
rary dams  for  demolishing  them  after  they  have  served  their  purpose. 

The  floating  dipper  dredge  moves  itself  ahead  by  means  of  the 
dipper.  The  spuds  are  first  loosened  from  their  bearings,  and  the 
dipper  is  run  ahead  of  the  machine  and  rested  on  the  natural  ground 
surface  in  front  of  the  ditch.  The  spuds  are  then  raised,  and  the 
engines  operating  the  backing  drums  are  started;  the  dredge,  being 
free,  is  thus  pulled  ahead.  The  spuds  are  then  lowered,  the  dredge 
pinned  up,  and  excavation  resumed. 

In  timbered  country  the  right  of  way  must  be  cleared.  In  many 
cases  the  timber  cut  will  supply  sufficient  fuel  for  the  dredge.  The 
removing  of  logs  from  the  right  of  way  by  the  dredge  decreases  the 
output  materially ;  therefore  they  should  be  cut  in  lengths  of  16  to  20 
feet,  so  that  they  can  be  handled  readily.  Although  it  is  possible  to 
excavate  stumps  with  the  larger  floating  dredges  without  first  blast- 
ing them,  it  is  preferable  to  shatter  them  with  dynamite  to  avoid  the 
strain  on  the  machinery,  which  shortens  the  life  of  the  dredge.  Spe- 
cial care  must  be  taken  to  loosen  stumps  near  the  banks  of  the  new 
ditch,  for  the  dirt  can  be  dug  away  from  but  one  side  of  them. 


EXCAVATING   MACHINERY   USED   IN  LAND  DRAINAGE. 


21 


An  engineer,  a  craneman,  a  fireman,  and  one  or  more  deck  hands  are 
required  to  operate  a  dipper  dredge.  The  output,  loss  of  time  due  to 
breakdowns,  and  cost  of  repairs  depend  almost  wholly  upon  their  skill 
and  efficiency.  The  engineer  should  be  an  all-round  mechanic,  expe- 
rienced in  dredging.  The  cost  of  repairs  depends  largely  upon  the 
operator ;  a  careless  operator  will  cause  unnecessary  breakdowns.  It 
is  not  only  repairs  of  machinery  but  also  the  time  lost  that  increases 
the  cost  of  the  output.  It  is  well  established  that  it  is  not  the  initial 
cost  of  a  dredge  or  of  any  machine  that  consumes  the  profits,  but, 
rather,  the  operating  and  overhead  expenses.  So  important  a  matter 
is  the  efficiency  of  the  operator  and  craneman  that  where  mosquitoes 
are  troublesome  electric  fans  are  often  used. 

COST  OF  OPERATION. 

The  cost  of  dredge  work  depends  upon  a  number  of  factors :  The 
locality  of  the  work,  the  kind  of  soil,  repairs,  delays,  labor,  etc.,  influ- 
ence the  actual  cost  of  any  work.  If  the  water  level  can  naturally  be 
maintained  within  a  foot  or  so  of  the  surface  of  the  ground  the  cost 
of  excavation  can  be  reduced  very  low  with  this  type  of  machine. 
One  great  item  is  labor  cost. 

To  obtain  economical  results  there  must  be  a  certain  minimum 
yardage  for  the  dredge  to  remove,  for  installation  charges  must  be 
included  in  the  cost  of  the  work.  Any  excess  in  yardage  over  this 
minimum  would  reduce  the  cost  per  cubic  yard,  but  this  unit  cost 
decreases  very  slowly  as  the  yardage  increases  and  finally  becomes 
practically  fixed. 

Table  9  gives  for  each  size  of  dredge  the  size  of  job  above  which  an 
increase  in  amount  of  excavation  will  not  result  in  an  appreciably 
lower  cost  per  cubic  yard,  as  well  as  the  average  output  per  month,  the 
average  coal  consumption  per  10-hour  shift  (using  a  good  grade  of 
coal),  and  the  time  and  number  of  men  required  to  erect  and  dis- 
mantle. 
TABLE  9. — Data  useful  in  estimating  cost  of  excavation  by  floating  dipper  dredge. 


Number  of  men  and  time  required  — 

Average 

output 

Size  of 
dipper. 

Usual 
length  of 
boom. 

To  assemble  dredge  with 
old  hull. 

To  dismantle  dredge. 

Minimum 
economical 
yardage. 

per 
month 
with 
double 
shift 

coal 
consump- 
tion per 
shift. 

(52shifts). 

Cu.yds. 

Feet. 

Cu.yds. 

Cu.yds. 

Tons. 

3 

30 

8  men  30  davs  1          ... 

8  men  1J  weeks    ... 

100  000 

20  000 

H 

I4 

40 

300  000 

27  000 

2 

li 

50 

12  men  2  months       .  .  . 

12  men'  3  weeks  

500.000 

3?'  000 

3 

2 

55 

12  men  3J  months  

12  men  ,  1  J  months  

800,000 

47,000 

34 

? 

65 
80 

15  men,  3i  months  

15men,l|  months  
20  men  2  months 

1,000,000 
1  500  000 

55,000 
70  000 

3| 

4 

3i 

80 

do' 

do               

2,000,000 

75,000 

41 

*i 

90 

3,000,000 

80,000 

6 

Dredge  equipped  with  steel  pontoon  hull. 


22  BULLETIN   300,   U.    S.   DEPARTMENT  OF   AGRICULTURE. 

A  single  month  may  show  an  output  greatly  exceeding  the  above 
figures.  They  are  given  as  an  average  output  on  an  entire  project, 
including  all  delays  and  breakdowns. 

To  determine  the  haulage  costs  from  railroad  siding  to  the  place 
of  erection  the  length  of  haul  and  the  condition  of  roads  must  be 
known.  For  hull  material,  on  fairly  dry  roads,  from  800  to  1,000 
feet  B.  M.  is  considered  a  load;  and  for  machinery  about  3,000 
pounds.  It  is  often  necessary  to  use  the  8-wheeled  log  wagon  for 
hauling. 

In  operation  the  cable  expense  is  an  important  item.  A  hoisting 
cable  ordinarily  will  dig  60,000  yards  before  it  must  be  discarded, 
although  some  operators  count  on  using  one  a  month.  The  worn 
part  can  sometimes  be  used  for  backing  or  swinging  lines,  depend- 
ing on  the  place  of  the  break. 

When  new  equipment  is  purchased  some  contractors  expect  the  job 
to  pay  for  the  new  machine  as  well  as  render  a  profit.  Contractors 
using  old  equipment  have  little  advantage  over  purchasers  of  new 
equipment  when  bidding  for  work  unless  they  can  float  the  dredge, 
already  assembled,  to  the  new  job.  When  a  contractor  has  several 
machines  on  one  job  he  usually  installs,  at~a  central  point  accessible 
to  a  railroad,  a  completely  equipped  machine  shop,  so  that  he  can 
make  all  necessary  repairs  in  the  shortest  possible  time.  The  ex- 
pense of  this  plant  must  also  be  included  in  the  contract  price.  All 
successful  contractors  operate  two  shifts,  as  the  time  of  completion 
is  thereby  reduced  nearly  one-half  and  the  overhead  charges  re- 
duced accordingly.  The  output  of  the  day  shift  compared  with  that 
of  the  night  shift  is  a  disputed  question.  Some  operators  say  that 
the  day  shift  will  excavate  more  material  than  the  night  force,  while 
others  maintain  the  reverse;  some  assert  that  the  increased  output 
of  two  shifts  over  that  of  one  shift  is  about  75  per  cent.  The  night 
shift  has  the  advantage  that  minor  repairs  are  left  for  the  day 
shift ;  moreover  no  fuel  is  taken  on  during  the  night,  nor  do  visitors 
come  to  interfere  with  operations. 

Many  contractors  pay  their  crews,  in  addition  to  a  fixed  monthly 
wage,  a  bonus  for  every  yard  dug  over  a  certain  figure  fixed  for  each 
job  as  the  conditions  warrant.  These  bonuses  are  divided  among 
the  men  in  proportion  to  their  base  pay.  When  two  shifts  are  oper- 
ated the  bonus  is  computed  on  the  total  output  for  the  month  and 
not  on  the  output  per  shift.  Crews  are  usually  changed  from  day 
to  night  shifts  and  vice  versa  once  a  week.  When  operating  several 
machines  on  one  project,  contractors  save  by  shifting  men  from  a  ma- 
chine which  is  idle  on  account  of  repairs  to  other  machines  to  take 
the  place  of  the  crews  taking  time  off.  If  the  men  can  not  be 
used  on  other  machines  they  may  be  used  in  the  repair  shop.  Ex- 
perience has  shown  that  keeping  men  busy  reduces  breakdowns. 


EXCAVATING   MACHINERY   USED   IN   LAND   DRAINAGE.  23 

Of  the  various  sizes  of  floating  dredges,  most  operators  agree  that 
the  2J  or  3  cubic-yard  dredges  are  the  most  economical  in  cost  per 
cubic  yard. 

SELECTION   OF   DREDGES. 

The  floating  dipper  dredge  is  admirably  adapted  to  the  excava- 
tion of  drainage  ditches  having  sufficient  width  and  depth  and  the 
necessary  supply  of  water  for  floating  the  machine,  especially  where 
the  ground  is  swampy  or  covered  with  trees  or  stumps  rendering 
impracticable  the  use  of  teams  or  dry-land  machinery.  No  other 
type  of  excavator  is  so  well  fitted  for  digging  ditches  in  timbered 
country  or  where  large  stumps  will  be  encountered.  The  dipper 
dredge,  however,  is  not  well  adapted  to  digging  channels  of  less 
than  100  square  feet  in  cross-section,  although  it  is  used  in  the 
construction  of  smaller  ditches.  Standard  types  of  dipper  dredges 
are  not  adapted  to  digging  ditches  more  than  1,200  square  feet  in 
cross-section,  although  ditches  with  123-foot  base  and  11  feet  deep 
have  been  dug  with  a  90-foot  boom,  vertical-spud  dredge.  As  ordi- 
narily operated,  the  dipper  dredge  constructs  a  more  or  less  ragged 
and  irregular  ditch,  yet  in  the  hands  of  a  skilled  operator  very 
good  results  can  be  obtained. 

In  the  construction  of  ditches  in  the  Piedmont  section  of  the 
southern  Atlantic  Coast  States,  floating  dipper  dredges  equipped 
with  f-yard  dippers  and  30-foot  booms  and  mounted  on  sectional 
steel  hulls  are  used  rather  extensively.  The  ditches  have  ordinarily 
a  top  width  of  from  14  to  20  feet  and  a  length  of  5  or  6  miles, 
involving  the  removal  of  100,000  cubic  yards  or  more  of  earth. 
Since  the  ditches  frequently  cross  an  old  channel,  the  floating  dredge 
is  better  adapted  to  this  work  than  dry-land  machines.  Contractors 
state  that  the  cost  of  installing  a  dredge  of  this  size  on  a  job  is  about 
$5,000.  To  justify  the  installation  of  this  size  of  machine,  a  job 
should  cost  about  $20,000  or  more. 

A  l|-yard  dredge  having  a  40  or  50  foot  boom,  a  hull  20  to  22  feet 
wide,  and  a  draft  of  3  feet  is  an  economical  machine  for  digging 
small  ditches.  A  dredge  of  this  size  will  excavate  a  ditch  through 
timbered  land  cheaper  than  any  other  type  of  small  excavating 
machine.  On  a  project  adapted  to  floating  dredges,  with  plenty  of 
water  for  floating  the  machines,  and  where  there  are  a  few  small 
laterals  with  bottom  \vidths  of  4  or  5  feet  and  ranging  in  depth 
from  7  to  8  feet,  the  construction  of  these  small  laterals,  if  dug  by 
the  machine  used  on  the  larger  ditches,  will  invariably  cost  more 
per  cubic  yard  than  ditches  with  14- foot  bottoms,  owing  to  the  excess 
yardage  which  must  be  removed  by  the  dredge. 

The  size  of  the  dredge  that  should  be  used  depends  upon  various 
factors.  Not  only  the  greatest  and  least,  but  the  intermediate  cross- 


24  BULLETIN   300,   U.   S.   DEPARTMENT  OF  AGRICULTURE. 

sectional  dimensions  of  the  proposed  ditch  should  be  known  and  the 
relative  amount  of  each  class,  also  the  width  of  berm  and  the  side 
slopes.  On  small  ditches  the  spread  of  the  spud  feet  usually  deter- 
mines the  width  of  berm.  The  total  amount  of  excavation,  nature 
of  the  material,  and  whether  the  dirt  is  to  be  dumped  on  one  or  both 
sides  are  factors  that  must  be  considered.  A  knowledge  of  the  depth 
of  water  which  can  be  maintained  at  a  minimum  expense  is  also 
necessary,  and  information  as  to  the  number  and  size  of  stumps  to  be 
encountered  is  of  the  highest  importance.  Owing  to  the  expense  of 
knocking  down,  transporting,  and  setting  up  a  dredge,  it  is  necessary 
to  select  or  use  one  of  the  size  that  will  do  the  most  work  at  one 
building.  This  requires  intimate  knowledge  of  the  layout  of  the 
proposed  work  and  of  the  accessibility  of  the  different  portions. 

The  size  of  ditch  best  fitted  for  any  size  of  dredge  is  one  which 
gives  just  sufficient  clearance  for  the  moving  of  the  dredge.  The 
ditch,  at  its  top,  should  be  about  4  feet  wider  than  the  hull  of  the 
dredge. 

It  is  the  opinion  of  many  contractors  that  the  use  of  dredges  with 
hulls  18  feet  wide  or  less  is  to  be  avoided,  except  where  the  ground 
is  so  hard  that  the  bank  spuds  rest  firmly  and  bear  the  weight  of 
the  swinging  load ;  in  soft  ground  it  may  be  cheaper  to  use  a  wider 
hull,  even  though  it  is  necessary  to  make  the  ditch  wider  than  speci- 
fied. 

To  determine  the  particular  dredge  required  for  a  project,  it  is 
necessary  to  know  the  limitations  of  the  various  sizes  of  machine 
and  the  distances  a  machine  of  a  given  length  of  boom  and  dipper 
handle  will  dig  below  water  line  and  dump  above  water  line.  The 
hull,  of  course,  must  be  of  such  dimensions  as  to  accommodate  ma- 
chinery of  the  required  dimensions.  Table  10  gives  the  approximate 
dimensions  of  different  sizes  of  dipper  dredges  equipped  with  differ- 
ent types  of  bank  spuds.  The  dimensions  vary  somewhat  for  different 
makes  of  dredges.  The  size  of  hull  can  be  varied  to  suit  the  needs  of 
the  particular  job.  When  material  is  excavated  it  swells  and  occupies 
more  space  than  before  removal.  The  amount  of  swell  varies,  with 
the  excavated  material,  from  10  to  25  per  cent.  The  angle  of  repose 
of  the  excavated  material  varies  with  the  character  of  that  material. 
It  is  usually  taken  as  a  1  to  1  or  1|  to  1  slope,  but  in  soft,  wet  ma- 
terial the  angle  of  repose  is  much  flatter. 


EXCAVATING    MACHINERY   USED   IN   LAND   DRAINAGE.  25 

TABLE  10. — Dimensions  and  limitations  of  operation  of  floating  dipper  dredges. 


Size  of 
dip- 
per. 

Length. 

Depth 
it  will 
dig 
below 
water. 

Height 
it  will 
dump 
above 
water. 

Distance 
center  of 
hull  to 
center  of 
dump. 

Telescopic  or 
Hull.                                 convertible 
spuds. 

3oom. 

Dipper 
handle. 

Bank  spuds. 

Vertical  spuds. 

Verti- 
cal 
range 

plat- 
form. 

Spread 
of 
plat- 
form. 

Size  of  hull. 

Lum- 
ber M 
feet. 

Size  of  hull. 

Lum- 
ber M 
feet. 

Cu.yds 

I 

1 

1J 
2 

21 

3 
31 

4 
5 

Feet. 
20 
22 
25 
25 
130 
35 
30 
35 
140 
45 
50 
55 
60 
35 
40 
45 
150 
55 
60 
65 
70 
40 
45 
50 
55 
160 
65 
70 
75 
80 
85 
90 
40 
45 
50 
55 
60 
65 
170 
75 
80 
85 
90 
60 
65 
70 
75 
180 
85 
90 
60 
65 
70 
75 
80 
85 
90 
75 
80 
185 
90 
85 
190 
95 

Feet. 
14 
15 
17 
19 
21  to  22 
23  to  25 
21 
25  to  27 
28  to  30 
31  to  33 

8 

40 
26 
28  to  30 
31  to  33 
31  to  36 
35  to  39 
38  to  40 
38  to  43 
46 
28 
31 
34  to  37 
37  to  40 
40  to  43 
43  to  46 
46 
49 
52 
55 
58 
28 
31 
34 
37 
39  to  43 
42  to  46 
46  to  49 
49  to  52 
50  to  52 
55 
58 
40 
43 
46  to  50 
49  to  53 
52  to  56 
55  to  59 

4( 
43 
46 
49 
52 
55 
58 
53 
56 
59 
62 
59 
62 
65 

Feet. 
6 

?! 

8   to  10 
9   to  12 
10    to  14 
11 
10   to  13 
14   to  Hi 
151  to  16 
17i 
19 
201 
11 
13   to  14 
15  to  16 
16  to  17 
17   to  181 
18   to  20 
18  to  211 
18 
13 
144. 
16  to  174 
17J  to  19 
19  to  204. 
201  to  22 
22 
231 
25 
261 
28 
13 

Ml 

16 

18   to  203 
18   to  22 
20   to  231 
231  to  25 
22   to  25 
261 
28 
20 

21* 

23   to  24 
241  to  251 
26   to  27 
271  to  281 
29 
20 
22 

% 

ii! 

29^ 

9 

28} 
30 
283 
30 
31^ 

Feet. 
5  to  7 
6  to  8 
7  to  9 
6  to   8 
8   to  10^ 
91  to  12 
9   to  12 
114.  to!5 
12  to  17 
15    to  18 
18  to  21 
21   to  24 
24   to  27 
14 
12   to  161 
15   to  19 
17    to21J 
20   to  24 
22   to  26 
23   to  29 
26 
10   to  13 
13  to  15 
15   to  22 
18  to  241 
21   to  27 
24  to  291 
27   to  30 
30   to  33 
33   to  36 
36   to  39 
39   to  42 
10   to  13 
13   to  15 
|15   to  18 
|18   to  21 
i22   to  261 
23   to  29 
26   to  311 
130  to  341 
b   to  36 
'36   to  39 
39   to  42 
21   to  24 
24   to  27 
|27   to  32 
'30   to  341 
33   to  37 
341  to  391 
39   to  42 
21   to  24 
24   to  27 
27   to  30 
30   to  33 
133   to  36 
36   to  39 
39   to  42 
1  291  to  34 
32   to  361 
341  to  39 
i37   to  411 
34   to38J 
361  to  41 
39   to  43 

Feet. 
18  to   20 
20   to   22 
22J  to   25 
20  to   25 
25  to    31 
28  to    35 
29  to    34 
33  to    iO 
37  to    44 
11  to    -19 
45  to    50 
50  to    55 
55  to    60 
35  to    40 
35  to    15 
40  to    49 
45  to    5. 
50  to   60 
55  to    65 
60  to    70 
70  to    75 

Feet. 
48X10X4 
48X11X4 
48X12X4 
51X12X41 
56X14X41 
56X16X4 
65X14X5 
66X16X5 
70X17X5 
70X19X5 
70X22X5 
80X24X5 
80X26X5 
72X16X5 
75X18X61 
75X20X61 
80X22X6| 
80X2  tX61 

B.    M. 

Feet. 

B.    M. 

Feet. 

Feet. 



51X18X41 
56X20X4 
56X20X-4 
65X22X5 
65X23X5 
70X25X5 
70X27X5 
70X30X5 
80X32X5 
80X34X5 

20 
22 

25 

28 

30 
31 
36 

40 

12 
li 
16 
18 

33 

38 
43 

48 

36 
40 
46 
50 

75X26X61 
75X28X61 
80X30X61 
80X32X61 

52 
5f 
63 
67 

16           44 

18           49 
20           54 
22           59 

| 

96X34X7 
85X28X6J 
85X30X61 
85X30X7 
85X32X7 
90X34X7 
90X36X7 
100X40X7 
100X44X7 
100X46X7 
100X46X7 
110X48X7 
85X30X7 
85X32X7 
90X34X7 
90X36X7 
90X35X71 
95X37X71 
95X39X71 
100X41X71 

35  to   40 
40  to   45 
45  to    55 
50  to    61 
54  to    66 
59  to    71 
65  to    70 
70  to   75 
75  to   80 
80  to   85 
85  to    90 
35  to    40 
40  to   45 
45  to    50 
50  to   55 
54  to   66 
59  to   71 
63  to    76 
67  to    80 
75  to   85 
80  to    85 
85  to   90 
55  to    60 
60  to   65 
63  to    77 
67  to    83 
71  to   88 
76  to   94 
85  to   90 
55  to   60 
60  to    65 
65  to   70 
70  to    75 
75  to   80 
80  to   85 
85  to   90 
68  to   83 
71  to   88 
76  to   94 
81  to   99 
76  to   94 
81  to   99 
85  to  104 

85X20X61 
85X22X61 
85X24X7 
85X26X7 
90X28X7 
90X30X7 
100X32X7 
100X34X7 
100X36X7 
100X38X7 
110X40X7 
85X22X7 
85X24X7 
90X26X7 
90X28X7 
90X29X71 
95X31X71 
95X33X71 
100X35X71 

"~57 
62 
70 
75 

""76 
86 
92 
105 

72 
76 
85 
91 

20           55 
22           60 
24           65 
26           70 

j 

•"        j  

L 

100 
108 
114 
125 

24 

26 
28 
30 

66 
71 
76 
81 

100X40X71 
110X42X71 
90X28X8 
90X30X8 
100X33X8 
100X35X8 
105X37X8 
110X40X8 
110X40X8 
90X30X8 
90X32X8 
100X34X8 
100X36X8 
100X38X8 
110X40X8 
110X42X8 
105X37X81 
110X39X81 
110X41X8} 
115X44X8^ 
115X41X9 
120X45X9 
125X49X9 

100X48X71 
110X50X71 
90X36X8 
90X38X8 
100X39X8 
100X41X8 
105X44X8 
110X46X8 
110X48X8 
90X38X8 
90X40X8 
100X42X8 
100X44X8 
100X46X8 
110X48X8 
110X50X8 
105X43X81 
110X45X81 
110X47X83 
115X49X83 
115X47X9 
120X51X9 
125X55X9 

105 
110 
120 
135 

130 
135 
150 
165 

28 
30 
32 
34 

76 
81 
86 
92 

125 
138 
145 
160 
155 
180 
200 

150 
165 
175 
190 
190 
215 
240 

30 
32 
34 
36 
34 
36 
38 

83 
88 
93 
99 
93 
100 
107 

Length  of  boom  ordinarily  used  wirh  corresponding  size  of  bucket. 


26  BULLETIN   300,   U.    S.    DEPARTMENT   OF   AGRICULTURE. 

By  adopting  special  methods  contractors  sometimes  accomplish 
seemingly  impossible  work  with  dredges.  In  a  drainage  district5 
having  a  main  ditch  ranging  in  size  from  a  14- foot  base  with  J  to  1 
side  slopes  to  a  35-foot  base  with  1  to  1  side  slopes,  a  1^-yaTd  bank- 
spud  dipper  dredge  having  a  55-foot  boom  and  mounted  on  a  30-foot 
hull  was  used.  The  berms  specified  were  10  feet  in  width.  The  top 
width  of  the  ditch  at  its  largest  section  was  55  feet.  The  distance  from 
center  to  center  of  spud  feet  was  about  59  feet,  which  did  not  quite 
give  sufficient  reach  for  the  feet  to  span  the  ditch.  These  conditions 
were  met  by  the  contractor  in  the  following  manner :  One-half  of  the 
width  of  the  ditch  was  dug  for  the  entire  length  of  the  wide  section, 
all  of  the  material  being  placed  on  one  side.  The  dredge  then 
"kicked"  back  to  the  beginning.  The  contractor  then  bolted  two 
logs  22  feet  long  and  having  a  minimum  diameter  of  15  inches  to  the 
spud  foot  next  to  the  excavated  channel.  The  logs  were  laid  parallel 
on  opposite  sides  of  the  jack  arm,  one  end  of  each  log  being  placed  on 
the  hull  while  the  other  rested  on  the  bank.  The  outer  ends  of  the 
logs,  which  extended  several  feet  beyond  the  spud  foot,  were  bolted 
together  on  both  top  and  bottom  with  6  by  8  inch  timbers.  Timbers 
of  the  same  size  were  placed  against  each  side  of  the  spud  foot  and 
bolted  to  the  logs.  Thus  the  machine  had  a  spud  bearing  on  both 
banks  and  still  maintained  the  specified  berm.  This  unique  attach- 
ment eliminated  the  necessity  of  installing  a  longer  boom,  with  possi- 
ble overloading  of  the  machinery. 

On  another  project  a  contractor  using  a  floating  dipper  dredge  was 
unable  to  dispose  of  all  the  excavated  material.  A  centrifugal  pump 
and  gasoline  engine  were  mounted  on  a  barge,  and  by  forcing  water 
through  a  nozzle  sufficient  pressure  was  obtained  to  wash  the  exca- 
vated material  back  over  the  adjacent  land  away  from  the  ditch. 
This  method  is  economical  in  reducing  inconveniently  large  waste 
banks.  On  very  wide  ditches,  over  80  feet  in  base  width,  in  order  to 
obtain  a  stable  toe  for  the  large  waste  bank,  pilot  cuts  are  often  made 
and  the  excavated  material  placed  to  form  the  inner  toe  of  the  waste 
bank. 

Frequently  the  overhead  and  width  clearances  of  a  dredge  must  be 
known  to  determine  whether  the  dredge  can  pass  a  bridge.  This  in- 
formation is  given  in  Table  11. 

6Eng.  Rec.,  vol.  75   (1917),  p.  77. 


EXCAVATING   MACHINERY   USED   IN   LAND   DRAINAGE.  27 

TABLE  11. — Clearance  of  dredges  fitted  icith  telescopic  or  convertible  spuds. 


Ca- 
pacity 
of 
dipper. 

Overhead  clearance. 

Width  clearance. 

Telescopic 
bank 
spud. 

Vertical 
spud. 

Convert- 
ible 
spud. 

Telescopic 
bank 
spud. 

Vertical 
spud. 

Cu.  yds. 

1» 

!J 
? 

5 

Feet. 

18 

Feet. 

18 

Feet. 

Feet. 
14  to  16 

Feet. 
20  to  22 

18 
.    19 
20 
21 
22 

20 
22 
24 
26 
30 

17* 
20 
20J 
21 
22 
23 

16  to  21 
20  to  26 
26  to  32 
31  to  37 
35  to  42 

24  to  29 
28  to  34 
32  to  38 
37  to  43 
41  to  48 

22 

22 

34 
38 

39  to  46 
43  to  55 

45  to  51 
49  to  61 

The  overhead  clearance  is  figured  from  bottom  of  hull  to  top  of 
cabin,  with  A  frame  lowered  and  with  spuds  unshipped.  Figures  for 
width  clearance  are  for  minimum  and  maximum  lengths  of  boom. 

When  designing  a  ditch  the  engineer  should  always  have  in  mind 
the  limitations  of  the  type  and  size  of  machine  adapted  to  the  work. 
Consistent  with  other  considerations  a  ditch  system  should  be  so  de- 
signed as  to  give  the  contractor  the  greatest  amount  of  excavation  for 
a  given  size  of  dredge.  This  point  may  be  illustrated  by  a  practical 
example :  Suppose  a  ditch  is  designed  with  a  bottom  width  varying 
from  16  to  46  feet  and  a  cut  of  7  feet  throughout  the  length  of  15 
miles.  The  ditch  as  planned  is  too  wide  at  its  lower  end  to  be  con- 
structed by  a  dredge  of  ordinary  size,  unless  it  be  equipped  with  tele- 
scopic or  convertible  power  spuds.  By  making  the  cut  deeper  at 
the  lower  end  the  width  of  the  ditch  can  be  made  considerably  less, 
and  a  dredge  of  ordinary  size  can  dig  the  ditch  throughout.  To  use 
two  dredges  of  different  sizes  on  such  a  comparatively  small  job 
would  increase  the  unit  cost. 

If  ditches  are  planned  for  one  machine  to  do  all  the  work  the  cost 
of  construction  will  be  reduced,  but  the  time  required  to  do  it  all  with 
one  machine  may  be  so  great  that  the  district  would  rather  pay  the 
additional  cost  involved  in  installing  two  plants. 

A  contract  may  include  a  number  of  ditches,  all  but  one  of  which 
are  suited  to  a  given  size  of  machine,  this  one  being  too  wide  to  be 
cut  by  the  dredge  at  one  cutting,  with  yardage  insufficient  to  justify 
the  installation  of  another  dredge.  That  difficulty  may  be  overcome 
by  making  a  double  cut,  which,  however,  requires  the  use  of  either 
vertical  or  convertible  spuds. 

Parallel  small  lateral  ditches,  each  having  a  separate  outlet  into  a 
large  main  canal,  are  difficult  to  construct.  The  dredge  required  to 
excavate  the  main  ditch  is  too  large  for  the  economical  construction 


28  BULLETIN   300,  IT.   S.   DEPARTMENT  OF  AGRICULTURE. 

of  the  laterals,  and  the  latter  are  too  small  and  too  short  to  warrant 
installation  of  a  separate  machine.  The  laterals  are  usually  con- 
structed after  the  main  canal  has  been  completed,  so  that  a  dam  must 
be  built  in  the  main  ditch  to  hold  the  water  at  the  desired  elevation 
when  constructing  the  laterals.  Where  topography  and  other  con- 
ditions permit,  a  better  plan  would  be  a  supplementary  ditch  parallel 
to  the  main  channel,  with  short  laterals  of  such  length  as  not  to  re- 
quire dams  to  maintain  the  water  level.  With  such  a  layout  the  sup- 
plementary canal  and  laterals  may  be  constructed  by  one  dredge  much 
cheaper  than  if  each  lateral  had  an  outlet  into  the  main  ditch.  The 
topography  of  the  ground  would  determine  the  feasibility  of  this 
plan  and  the  length  of  the  laterals.  The  water  should  be  at  such 
height,  if  practicable,  that  not  over  2  feet  of  face  is  exposed. 

THE  FLOATING  GRAB-BUCKET  DREDGE. 

The  floating  grab-bucket  dredge  differs  from  the  dipper  type  in  the 
appliances  for  handling  the  material  and  in  the  operating  machinery. 
Instead  of  using  a  dipper  and  dipper  handle,  an  orange-peel  or  a 
clam-shell  bucket  is  suspended  from  the  end  of  the  boom.  The  bucket 
of  orange-peel  type  is  generally  used  for  drainage  work,  as  it  operates 
more  satisfactorily  in  stumpy  ground  and  on  materials  of  varying 
density. 

The  floating  grab-bucket  dredge  may  be  of  the  gravity-return  or 
of  the  bull- wheel-swing  type,  and  it  can  be  operated  by  a  single  engine 
of  uniform  speed.  Hoisting  and  swinging  are  accomplished  by  drums 
operated  by  friction  clutches.  In  Plate  II,  Figure  1,  a  typical  orange- 
peel  dredge  is  shown. 

A  much  longer  boom  can  be  used  with  the  grab-bucket  dredge  than 
with  the  dipper  dredge.  From  75  to  90  feet  is  about  the  maximum 
length  of  boom  that  can  be  successfully  operated  on  a  dipper  dredge, 
while  booms  as  long  as  240  feet,  operating  6-yard  buckets,  have  been 
used  on  grab-bucket  dredges.  This  feature  is  of  especial  importance 
in  levee  construction,  where  it  is  desired  to  deposit  the  material  as  far 
from  the  stream  as  possible. 

While  the  dipper  dredge  pulls  itself  ahead  by  means  of  the  dipper, 
some  kind  of  pull-ahead  line  is  necessary  with  a  grab-bucket  dredge. 
Generally  three  auxiliary  drums  are  provided,  two  for  operating  the 
spuds  and  one  for  drawing  the  pull- ahead  line  which  is  secured  to 
the  bucket.  The  bucket  is  dropped  into  the  material,  the  hoisting 
line  is  slackened,  and  the  pull-ahead  line  is  drawn  taut,  pulling  the 
dredge  ahead.  In  other  cases  the  pull- ahead  line  may  be  anchored  to 
a  deadman  buried  some  distance  ahead  of  the  machine. 

For  depositing  at  some  distance  from  the  edge  of  the  ditch  ma- 
terial excavated  by  floating  grab-bucket  dredges  equipped  with  short 


EXCAVATING    MACHINERY   USED   IN   LAND   DRAINAGE.  29 

booms,  steel  chutes  have  been  used  successfully  in  the  reclamation  of 
swamp  lands  in  New  Zealand.  Two  chutes,  one  on  each  side  of  the 
hull,  are  mounted  on  steel  frames.  The  saturated  material  is  dropped 
into  the  upper  end  of  either  of  the  chutes,  which  have  slope  enough 
for  the  material  to  slide  down  and  fall  on  the  ground  some  distance 
from  the  edge  of  the  ditch. 

Owing  to  its  long  reach,  the  grab-bucket  dredge  is  often  used  for 
levee  construction.  It  is  not  extensively  used  for  the  excavation  of 
drainage  channels,  although  under  certain  conditions  it  can  be  used 
to  greater  advantage  than  can  the  dipper  dredge.  It  excels  in 
handling  the  muck  found  on  the  prairie  lands  of  southern  Louisiana 
and  in  certain  other  localities.  The  dipper  type,  however,  is  prefer- 
able for  digging  hard  soil  or  where  there  are  many  stumps. 

There  are  a  great  many  makes  of  both  orange-peel  and  clam-shell 
buckets.  The  dimensions  and  weights  for  the  several  makes  vary 
somewhat,  although  these  factors  differ  but  little  for  the  machines 
used  on  drainage  work. 

THE  DRAG-LINE  SCRAPER  EXCAVATOR. 

The  drag-line  scraper  excavator  is  a  dry-land  machine  that  has 
come  into  prominence  only  within  the  last  few  years.  It  has  made 
feasible  the  cheap  construction  of  much  larger  ditches  and  levees 
than  is  possible  by  the  use  of  any  other  type  of  machine. 

In  the  type  most  commonly  used  the  engine  platform,  engine  house, 
and  boom  are  connected  and  revolve  on  a  turntable  which  is  secured 
to  a  lower  platform  built  up  of  structural-steel  sections.  This  is 
known  as  the  revolving  or  rotary  type  and  is  illustrated  in  Plates  III, 
IV,  and  V.  Upon  the  upper  surface  of  the  lower  platform  is  riveted 
the  track  upon  which  the  swinging  circle  revolves,  and  in  its  center 
is  the  pivot  bearing.  The  turntable  is  a  steel-frame  circle  supported 
by  several  dolley  wheels  which  rest  upon  the  track.  The  number  of 
dolley  wheels  varies  with  the  different  makes  as  well  as  with  the  size 
of  machine,  a  sufficient  number  being  used  in  each  case  to  insure  the 
required  bearing  for  steady  operation.  The  upper  platform,  which 
is  also  built  up  of  standard  steel  sections,  is  held  to  the  lower  platform 
by  the  central  pivot. 

The  rotation  or  swinging  of  the  machine  is  accomplished  by  two 
methods.  The  method  almost  universally  used  is  the  rack-and-pinion 
method.  On  the  lower  platform  is  a  circular  rack  with  cut  or  cast 
steel  gears.  In  Plate  III,  Figure  1,  both  the  rack  and  dolley  wheels 
are  shown.  On  the  upper  platforr  i  are  the  swinging  engines  which 
drive  a  pinion,  which  in  turn  meshes  into  the  rack  (PI.  Ill,  Fig.  2)  on 
the  lower  platform.  By  this  mode  of  rotation  the  machine  can  revolve 
any  number  of  times  in  either  direction. 


30  -BULLETIN   300,   U.    S.   DEPARTMENT  OF   AGRICULTURE. 

There  is  also  the  cable-swing  excavator  in  which  the  swinging  is 
done  by  means  of  two  cables  having  dead  ends  on  the  perimeter  of 
the  turntable.  These  cables  run  to  drums  on  the  upper  platform 
which  are  operated  by  the  swinging  engines.  This  mode  of  swing  is 
not  as  popular  as  the  rack-and-pinion  swing,  due  to  the  fact  that 
although  the  machine  can  revolve  nearly  a  full  circle,  it  must  return 
in  the  direction  from  which  it  has  revolved.  The  cable-swing  machine 
is  the  lighter. 

In  the  nonrotating  drag-line  machine  the  engine  platform  is  fixed ; 
the  boom  is  pivoted  at  its  lower  end  and  is  the  only  part  of  the  ma- 
chine which  swings.  This  type  is  illustrated  in  Plate  VII,  Figure  2. 

The  crew  necessary  to  operate  a  drag-line  excavator  consists  of 
two  men,  an  operator  and  a  fireman  on  a  steam  machine,  an  operator 
and  an  oiler  on  a  gasoline  or  electrically  driven  machine.  In  addition, 
two  or  more  trackmen  are  required,  except  in  the  case  of  the  walking 
and  caterpillar  types. 

Where  the  ground  is  uneven  or  cut  up  with  old  channels  and  surface 
ditches  it  is  necessary  for  all  excavators  not  of  the  rotary  type  to  block 
or  bridge  across  the  depressions,  laying  heavy  timbers  on  which  to 
move  the  machine.  When  a  machine  weighs  25  tons  or  more  the 
expense  of  providing  a  solid  foundation  is  an  important  item.  In  the 
rotary  type  of  excavator  the  machine  can  be  revolved  to  build  its  own 
foundation  of  earth. 


THE   ROTARY   TYPE. 

METHODS    OF   PROPELLING. 


There  are  three  kinds  of  mountings  used  with  revolving  drag-line 
excavators.  The  one  in  general  use  is  the  skid-and-roller  mounting. 
The  machine  travels  on  a  track  of  plank  laid  on  the  ground  and  is 
moved  by  partly  filling  the  bucket  and  using  it  as  an  anchor  upon 
which  to  pull.  Plate  IV,  Figure  1,  shows  a  machine  with  skid-and- 
roller  mounting  transferring  a  section  of  its  track  ahead  so  that  it  can 
move  up.  The  skid-and-roller  mounting  can  be  used  under  all  ma- 
chines except  those  weighing  over  80  tons.  Black-gum  rollers  are 
ordinarily  used,  being  cheaper  and  easier  to  obtain  than  hard  maple. 
Heavy  machines  are  very  hard  on  wooden  rollers ;  consequently  trucks 
running  on  tracks  are  used  for  the  large  sizes.  Where  trouble  is 
expected  from  crushing  and  splitting  of  wooden  rollers,  6-inch  steam 
pipe  may  be  used  instead.  In  Figure  1  is  shown  a  sectional  track  for 
a  drag-line  excavator  with  skid-and-roller  mounting.  This  figure, 
taken  from  Engineering  and  Contracting,  volume  46  (1916),  page 
158,  shows  the  arrangement  of  the  track  units.  Each  unit  is  24  feet 
long,  10  being  used  for  the  machine  in  question,  5  under  each  side. 
It  will  be  noted  from  the  figure  that  the  ends  of  the  top  timbers  are 


EXCAVATING    MACHINERY    USED    IN    LAND    DRAINAGE. 


31 


staggered,  while  the  ends  of  the  bottom  timbers  are  placed  even.  The 
staggered  ends  make  possible  a  more  rigid  connection  and  also  provide 
means  of  taking  curves  while  still  preserving  a  solid  bearing  for  the 
rollers.  The  rigging  to  pick  up  the  track  sections  consists  of  f-inch 
chain,  two  pieces  3  feet  9  inches  long  and  two  pieces  3  feet  3  inches 
long.  With  uneven  chain  lengths  one  end  of  the  track  section  is 
held  higher  than  the  other,  which  lightens  the  labor  in  making 
track  connections.  It  is  asserted  that  a  section  can  be  swung  ahead 
and  placed  in  one  and  one-half  minutes.  With  this  type  of  track 
a  contractor  has  moved  his  machine  2,600  feet  in  10  hours. 

,-Heavy  Hook  from  1+  X  if'St 
'    "  '~IO'0"ro  end  of  Cable 


V-  4"Ring 
~ ' ffings 


Machine  should  go  in  this  d friction >-      f 

,fU-Boft^  ,'2x/3"Machine  Bolts  (countersunk  heads) 


of  bottom  p/anks  are  shown  by  dotted  tines-' 
Top  Timber  5"x IG"x 20' 0" Heart  Pine.  Bo11om  Timbers  2£'x/6'x20'0"HeartP/ne 
Cross  Ties  6Hx8x8'0"SfdRR.Ties 

FIG.  1. — Sectional  track  for  a  rotary-scraper  excavator  with  skid  and  roller  mounting. 

A  drag-line  excavator  mounted  on  skids  and  rollers  moves  ahead 
by  pulling  on  the  bucket  left  partly  filled  in  the  earth  to  be  excavated, 
the  anchor  blocks  in  front  of  the  machine  having  been  previously 
removed.  There  are  instances  where  the  surface  material  may  be 
so  soft  as  to  preclude  this  method  unless  the  top  material  is  first 
excavated  down  to  a  stiff  subsoil.  To  avoid  this  extra  labor  it  is 
possible,  after  swinging  the  machine  through  180°,  to  hitch  the 
bucket  to  a  cable  run  through  the  bed  of  the  machine  and  anchored 
to  the  track,  and  thus  to  move  the  machine  by  backing  it  up.  The 
weight  on  the  track  of  the  machine  that  is  being  moved  will  ordinarily 
furnish  sufficient  anchorage.  This  method  has  been  used  successfully 


32  BULLETIN    300,    U.    S.    DEPARTMENT   OF   AGRICULTURE. 

in  muskeg  swamps,  thus  sparing  the  excavation  of  several  feet  of 
the  soft  surface  to  reach  the  underlying  clay. 

The  caterpillar  or  apron-traction  mounting  eliminates  the  track- 
men necessary  with  the  skid-and-roller  mounting.  For  small  ma- 
chines two  caterpillars  (PL  IV,  Fig.  2)  are  commonly  used.  In  one 
make  of  light  drag-line  excavator  a  combination  of  two  wheels  and 
two  caterpillars  is  used.  The  heavier  machines  require  four  cater- 
pillars. A  skillful  operator  can  turn  a  drag-line  excavator  mounted 
on  caterpillars  in  its  own  length. 

Large  machines  usually  are  mounted  on  four  4-wheeled  equalizing 
trucks  (PI.  V,  Fig.  1),  though  any  size  may  be  furnished  with  this 
mounting  if  desired.  These  trucks  may  all  be  nonpropelling,  in 
which  case  the  machine  moves  in  the  same  way  as  i£  mounted  on  skids 
and  rollers,  or  two  of  the  trucks  may  be  driven  by  power  from  the 
main  engines  of  the  machine.  On  the  smaller  machines  one  truck 
usually  is  mounted  under  each  corner  of  the  lower  platform,  while 
on  the  larger  machines  three  of  the  trucks  are  generally  mounted  on 
an  equalizing  beam.  This  latter  method  is  preferable,  as  by  its  use 
the  weight  of  the  machine  is  always  evenly  distributed,  and  thus 
the  platforms  are  not  subjected  to  severe  stresses. 

There  is  another  type  of  mounting  in  which  a  novel  method  of 
moving  is  employed.  Attached  to  the  upper  platform  and  extending 
through  the  machine  in  a  direction  at  right  angles  to  that  of  the  boom 
is  a  heavy  steel  shaft,  on  each  end  of  which  is  a  wheel  segment  (PL 
V,  Fig.  2).  The  shaft  also  carries  a  large  gear  wheel  which  meshes 
with  a  pinion  on  the  loading-drum  shaft  of  the  main  engine.  Sus- 
pended from  the  middle  arm  of  each  segment  by  means  of  a  carrying 
beam  and  chains  is  a  long  shoe,  which  affords  a  bearing  for  the  seg- 
ment as  it  rotates  and  propels  the  machine  forward.  To  move  in 
a  given  direction  the  excavator  is  rotated  until  the  boom  is  pointing 
in  the  opposite  direction ;  the  side  shoes  are  lowered  by  rotating  the 
shaft  supporting  the  wheel  segments,  and  the  weight  of  the  machine 
is  thrown  on  to  the  side  shoes;  the  segments  cause  the  machine  to 
rise  and  move  ahead  8  feet.  This  excavator  has  an  advantage  over 
other  types  of  self-propelling  machines  in  that  it  can  move  in  any 
direction.  The  machine  can  be  walked  at  a  rate  of  25  to  30  feet  a 
minute.  When  digging,  the  machine  rests  upon  a  large  circular  base. 
The  average  bearing  pressure  when  working  is  from  3J  to  4^  pounds 
per  square  inch. 

All  self-propelling  machines  do  without  trackmen  when  working 
over  reasonably  stable  ground.  In  soft  ground  extra  bearing  sur- 
face may  be  required  to  prevent  the  machine  from  sinking.  On  one 
occasion  a  3-yard,  70-foot  boom,  walking,  drag-line  excavator,  work- 
ing in  unusually  soft  ground,  required  additional  bearing  surface. 
Eight  pontoons  were  used,  each  7  feet  by  30  feet,  the  machine  always 


Bui.  300,  U.  S.  Dept.  of  Agriculture. 


PLATE  III. 


FIG.   I. — RACK  AND  DOLLEY  WHEELS. 


FIG.  2.— MECHANISM   FOR  OPERATING   PINION   AND  SWINGING 
DEVICE  FOR  RACK-AND-PINION  TYPE  OF  DRAG-LINE  EXCAVATOR. 


Bui.  300,  U.  S.  Dept.  of  Agriculture. 


PLATE  IV. 


D-3281 

FIG.     I.— DRAG-LINE     EXCAVATOR     ON     SKID-AND-ROLLER     MOUNTING 
TRANSFERRING  A  SECTION  OF  TRACK  AHEAD. 


FIG.  2.— DRAG-LINE  EXCAVATOR   MOUNTED  ON   TWO  CATERPILLARS. 


Bui.  300,  U.  S.  Dept.  of  Agriculture. 


PLATE  V. 


D-3322 

FIG.  I.— DRAG-LINE  EXCAVATOR  MOUNTED  ON  FOUR  4-WHEELED  TRUCKS. 


FIG.   2. — WALKING    DRAG-LINE    EXCAVATOR    MOVING   AHEAD. 


Bui.  300,  U.  S.  Dept.  of  Agriculture. 


PLATE  VI. 


D-3198 

FIG.  I. — ARRANGEMENT  OF  MACHINERY  ON  A  STEAM-OPERATED  DRAG-LINE 

EXCAVATOR. 


FIG.  2. — TWO-LINE  SCRAPER  BUCKET  OF  THE  SOLID  TYPE. 


EXCAVATING    MACHINERY    USED   IN    LAND   DRAIN  ACE.  33 

resting  on  three  pontoons.     With  three  pontoons  the  bearing  pressure 
was  1-J  pounds  per  square  inch. 

MACHINERY   AND  EQUIPMENT. 

The  power  equipment  of  the  drag-line  excavator  may  be  either 
steam,  gasoline,  or  electric.  On  drag-line  scraper  excavators  the 
internal-combustion  engine  has  been  used  with  success.  In  some 
places  the  quality  of  water  obtainable  for  use  in  boilers  and  the  ab- 
sence of  electric  power  may  determine  the  use  of  internal^combustion 
engines. 

The  machinery  for  operating  the  drag-line  excavator  is  placed 
on  the  upper  platform.  On  excavators  operated  by  internal-com- 
bustion engines  the  engine  may  be  either  gear-connected  to  the  oper- 
ating drum  or  belt-connected.  On  steam-operated  machines  the  main 
engines  are  of  the  double-cylinder,  friction-drum  type,  mounted  on  a 
structural-steel  base  (PL  VI,  Fig.  1).  The  main  engines  operate  the 
hoisting  and  loading  drums.  For  rotating  the  excavators,  separate 
engines  of  the  double-cylinder  type  are  used.  The  boilers  may  be 
either  vertical  or  locomotive  type.  Tables  12  and  13  show  the  dimen- 
sions of  engines,  boilers,  and  accessories,  average  fuel  consumption, 
and  shipping  weights  of  drag-line  excavators  of  various  capacities. 


34 


BULLETIN   300,    U.    S.    DEPARTMENT   OF   AGRICULTURE. 


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Digging-rope  diameter,  inche 
Standard  length,  feet  
Hoisting-rope  diameter,  incht 
Standard  length,  feet  
Main  engines  (double-cylinde 
Swinging  engines  (double-cy 
inder). 
Boiler  dimensions  

Water-tank  capacity,  gallons 
Water  consumption  in  1 
hours,  gallons. 
Coal  consumption  in  10  hour 

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EXCAVATING    MACHINERY    USED   IN   LAND   DRAINAGE. 
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35 


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36 


BULLETIN   300,    U.    S.    DEPARTMENT   OF   AGRICULTURE. 


BOOM. 


In  the  smaller  drag-line  excavators  the  boom  is  generally  con- 
structed of  two  channels  with  cross  bracing  (PI.  IV,  Fig.  1),  while  in 
the  larger  machines  two  cross-braced  lattice  girders  are  used  (PL  V, 
Fig.  1).  The  lower  ends  of  the  two  main  members  of  the  boom  are 
spread  apart  to  give  stability,  while  at  the  upper  end  the  two  mem- 
bers are  joined,  and  at  that  point  one  or  more  sheaves  are  placed.  On 
some  of  the  smaller  machines  the  top  of  the  boom  is  guyed  to  the  top 
of  the  A  frame,  which  is  located  near  the  front  of  the  main'engine. 
The  lower  ends  of  the  A  frame  are  bolted  to  the  platform ;  the  upper 
end  is  guyed  to  the  rear  corners  of  the  platform.  The  length  of  the 
boom  for  drag-line  excavators  varies  from  30  to  150  feet.  On  most 
machines  it  is  suspended  by  a  cable  running  to  a  drum  on  the  plat- 
form. For  raising  or  lowering  the  boom  this  drum  may  be  operated 
either  by  power  or  by  hand. 


BUCKET. 


There  are  various  forms  of  scrapey  buckets  made  for  use  with  drag- 
line excavators.  A  type  of  bucket  in  common  use  is  shown  in  Plate 
VI,  Figure  2.  This  bucket  can  be  operated  with  two  lines,  a  loading 
and  a  hoisting  line.  For  holding  the  bucket  horizontal  when  hoist- 
ing, a  patented  device  is  used  which  consists  of  a  cable  secured  to  the 
top  of  the  bucket  at  its  front  end,  which,  after  passing  through  a 
sheave  at  the  hoisting  connection,  runs  down  to  the  loading  bail. 
With  the  loading  line  kept  taut  the  bucket  maintains  a  horizontal 
position.  To  dump  the  bucket,  the  loading  line  is  merely  released. 

The  sizes,  weights,  and  approximate  prices  of  this  bucket  of  stand- 
ard type  are  shown  in  Table  14. 

TABLE  14. — Weights  and  prices  of  scraper  buckets. 


Ca- 
pacity. 

Width 
of 
cutting 
edge. 

Weight 
without 
teeth. 

Price. 

Cu.yds. 

Inches. 

Pounds. 

5 

36 

2,200 

$660 

1 

45 

2,500 

698 

11 

45 

2,800 

780 

li 

48 

3,200 

862 

2 

51 

4,850 

1,043 

2£ 

57 

5,850 

1,191 

3 

60 

6,550 

1,357 

3i 

60 

7,000 

1,510 

Many  operators  experience  trouble  with  scraper  buckets  of  the 
smaller  sizes  from  their  failure  to  clean  themselves  when  working 
in  sticky  clay.  To  obviate  this  a  skeleton  scraper  bucket  has  been 
made  for  very  sticky  clay.  This  bucket  cleans  itself  more  readily  in 


EXCAVATING   MACHINERY   USED   IN   LAND  DRAINAGE.  37 

sticky  material  than  the  solid  type.    It  is  made  in  five-eighths  cubic 
yard  size  only. 

OPERATION. 

It  is  impracticable  to  give  exact  figures  on  the  time  required  to 
assemble  a  drag-line  excavator,  as  the  time  will  vary  greatly  with 
the  make  of  machine,  the  length  of  boom,  and  the  style  of  mounting. 
Operators  generally  agree  that  more  time  is  required  to  assemble  a 
machine  mounted  on  caterpillars  than  one  mounted  on  skids  and 
rollers.  In  general,  the  time  required  for  8  men  to  assemble  a  drag- 
line excavator  varies  from  1  week  for  the  small  1-yard  walking  type 
to  6  weeks  for  a  3|-yard  caterpillar  machine.  The  actual  time  con- 
sumed in  erecting  a  3-yard,  70-foot  boom,  walking,  drag-line  ex- 
cavator equipped  with  internal-combustion  engines  was  2,137  man- 
hours.  The  assembling  by  12  men  took  19  days.  The  machine  made 
26  wagonloads  and  was  hauled  from  the  siding  to  the  project,  a  dis- 
tance of  3|  miles,  in  9  days. 

The  fuel  consumption  for  drag-line  excavators  depends  on  the 
character  of  the  soil  and  the  distance  of  hoisting.  The  average  con- 
sumption of  fuel  for  both  steam  and  gasoline  operated  drag-line  ex- 
cavators has  been  given  (Tables  12  and  13). 

Cable  expense  is  greater  on  drag-line  excavators  than  on  floating 
dredges.  The  life  of  cables  depends  largely  on  the  nature  of  the 
work,  regardless  of  the  size  of  machine.  Some  operators  consider 
the  life  of  a  digging  cable  as  about  25,000  cubic  yards  and  of  a  hoist- 
ing cable  about  100,000  cubic  yards.  Other  operators  state  the  life 
in  days  of  double-shift  operation.  In  earth  a  digging  rope  will  last 
from  2  to  3  weeks  and  a  hoisting  rope  from  1  to  2  months,  depend- 
ing on  the  number  of  shifts  and  the  condition  of  the  sheaves  and 
drums.  In  cemented  sand  and.  gravel  a  digging  rope  may  wear  out 
in  3  working  shifts;  usually  in  hard  material  its  life  is  not  longer 
than  10  shifts. 

The  life  of  a  cable  is  increased  by  proper  lubrication.  Incorrect 
lubrication  or  neglect  of  it  results  in  increased  wear  within  the  rope. 
Even  though  the  cable  may  appear  bright  and  in  good  condition, 
this  interior  wear  may  be  going  on.  The  lubricant  to  be  used  de- 
pends upon  the  work  which  the  cable  is  required  to  do.  A  hoisting 
cable  which  travels  at  considerable  speed  requires  a  different  lubri- 
cant from  track  cables  which  move  more  slowly. 

Drag-line  excavators  with  50  to  60  foot  booms  operate  more  rapidly 
than  machines  with  long  booms  of  90  feet  or  more.  Therefore  work 
which  requires  a  short  hoist  and  a  small  angle  of  swing  can  be  done 
more  rapidly  than  work  which  requires  a  long  hoist  and  a  large  angle 
of  swing.  Rack-and-pinion  swing  machines  have  an  advantage  over 


38 


BULLETIN   300,   U.    S.    DEPARTMENT  OF   AGRICULTURE. 


cable-swing  machines  in  that  when  a  swing  of  180  degrees  is  re- 
quired the  machine  can  complete  the  full  circle  and  return  to  the 
loading  point,  whereas  the  cable-swing  machine  must  be  reversed 
with  loss  of  both  time  and  energy. 

A  3-yard,  walking,  drag-line  excavator  having  an  80-foot  boom 
was  used  to  build  a  levee  averaging  15  feet  high.  The  machine 
traveled  on  the  berm,  taking  dirt  from  the  borrow  pit,  which  did 
not  exceed  10  feet  in  depth,  and  depositing  the  material  on  the  levee 
site.  The  angle  of  swing  was  about  145  degrees.  To  fill  the  bucket 
required  30  seconds ;  to  hoist,  swing,  and  dump  took  25  seconds ;  and 
30  seconds  were  required  to  return  to  the  borrow  pit.  The  entire 
operation  thus  consumed  85  seconds.  In  the  excavation  of  a  ditch 
36  feet  deep  in  which  the  angle  of  swing  was  90  degrees  and  the 
distance  of  hoist  60  feet,  a  2-yard  machine  with  a  75-foot  boom  was 
used.  Filling  the  bucket  required  25  seconds;  to  hoist,  swing,  and 
dump  required  20  seconds ;  and  to  return  to  fill  the  bucket  consumed 
20  seconds.  Thus  the  entire  time  of  one  operation  was  65  seconds. 

The  output  of  drag-line  excavators  of  various  sizes  will  vary 
greatly  with  the  length  of  boom,  depth  of  cut,  angle  of  swing,  and 
character  of  digging.  The  figures  given  in  Table  15  will  serve  as  an 
approximate  guide. 

TABLE  15. — Output  of  drag-line  excavators. 


Size  of 
bucket. 

Length 
of  boom. 

Economi- 
cal size  of 
job.* 

Output 
per  month, 
with 
double 
shift. 

Cu.yds. 

9 

f 
11 

Feet. 
40 
50 
60 
65 
70 
80 
100 

Cubic  yards. 
250,000 
300,000 
400,000 
500,000 
800,000 
1,000,000 
1,  500,  000 

Cubic  yards. 
18,000 
25,000 
30,000 
35,000 
40,000 
50,000 
70,000 

1  By  economical  size  of  job  is  meant  the  yardage  below  which  the  machine  can  not  be  installed  and 
operated  without  appreciably  increasing  the  cost  per  cubic  yard  of  excavation. 

These  figures  give  only  the  average  output,  including  all  lost  time ; 
they  may  be  greatly  exceeded  in  any  particular  month  during  con- 
tinuous operation.  On  one  contract  a  2-yard,  60-foot-boom  drag- 
line excavator  averaged  70,000  cubic  yards  a  month  with  double 
snift  while  building  a  levee  containing  1,100  cubic  yards  per  station. 

In  the  excavation  of  quicksand  great  care  must  be  used  in  handling 
the  bucket.  The  hoisting  line  is  kept  taut,  holding  the  back  end 
of  the  bucket  a  foot  or  so  above  the  sand,  while  the  cutting  edge,  or 
lip  of  the  bucket,  is  pulled  into  the  material.  The  output  of  a  ma- 
chine in  quicksand  is  about  one-fourth  that  in  ordinary  earth. 


EXCAVATING   MACHINERY   USED   IN   LAND   DRAINAGE. 


39 


Cost. — Table  16  gives  the  approximate  cost  of  rack-and-pinion- 
swing.  rotary  drag-line  excavators. 

TABLE  16. — Costs  of  rack-and-pinion-swHng,  rotary,  draff-line,  excavators,  1921. 


Size  of 
bucket. 

Length 
of  boom. 

Kind  of  power. 

Style  of  mounting. 

Approxi- 
mate cost. 

Cu.yds. 

Feet. 
30 

Oil  engine 

Caterpillar 

$11  000 

i 

40 

Steam 

do 

14*800 

| 

40 

Oil  engine  

do  

18*  650 

• 

40 

do..'... 

Walker  

15  700 

li 

45 

Steam 

Skid  and  rollers 

20  850 

[I 

45 

do 

Caterpillar 

29'  200 

2 

60 

.do  

Walker  

3l'oOO 

2 

60 

do 

Skid  and  rollers 

26  700 

2 

60 

do 

Caterpillar 

38  300 

2£ 

85 

.do  

Skid  and  rollers. 

38?300 

3 

60 

do 

Walker  .   . 

36  500 

31 

100 

do 

Skid  and  rollers 

46  900 

3* 

100 

.do  

Trucks  

56  800 

34 

125 

do 

do     . 

71  000 

5 

155 

do 

do 

97  500 

To  equip  boilers  for  burning  oil  fuel  costs  from  $450  to  $550,  de- 
pending on  the  size  of  the  boiler. 

CABLE-SWING   EXCAVATOR. 

A  cable-swing,  drag-line  excavator  (PI.  VII,  Fig.  1),  with  a  1-yard 
bucket  and  a  40- foot  boom,  has  been  placed  on  the  market  recently. 
The  machine  is  mounted  on  four  apron  tractors  and  is  operated  by  a 
55-horse  power,  two-cylinder  opposed-type  engine.  The  weight  is 
about  20  tons.  The  road  speed  is  one-half  mile  per  hour.  The  hoist- 
ing line  is  five-eighths  inch  and  the  loading  line  three-fourths  inch. 
The  machine  costs  $7,000,  including  the  bucket.  It  can  be  operated  by 
one  runner  and  one  oiler  and  consumes  about  35  gallons  of  gasoline 
in  10  hours  of  operation.  The  bucket  measures  35  inches  wide.  The 
over-all  clearance  of  the  machine  is  10  feet  3  inches  by  26  feet.  The 
machine  has  a  10-foot  turntable.  The  vertical  distance  from  the 
ground  to  the  fair  lead  sheaves  is  5  feet  2  inches,  and  the  horizontal 
distance  from  the  boom  pivot  to  the  center  of  the  turntable  is  6  feet 
9  inches.  The  machine  can  be  shipped,  assembled,  on  one  car.  Only 
the  boom  and  A  frame  are  dismantled  for  shipping. 

NONROTATING  DRAG-LINE  EXCAVATORS. 

A  light  drag-line  excavator  of  the  nonrotating  type  is  being  used 
rather  extensively  (PL  VII,  Fig.  2) .  The  machine  is  built  entirely  of 
steel.  The  main  frame  is  24  by  24  feet,  but  can  easily  be  made  wider 
or  narrower  if  desired.  The  platform  is  12  by  30  feet.  The  frame 
is  mounted  on  four  steel  wheels,  each  5  feet  high  and  3  feet  wide. 
The  boom  is  40  feet  long  and  can  be  extended  10  feet  more  if  it  is 
desired  to  use  the  machine  for  tile  trenching  or  lowering  large  tile 


40  BULLETIN   300,    U..  S.    DEPARTMENT   OF   AGRICULTURE. 

into  place.  A  45-horsepower,  2-cylinder,  opposed-type  oil  engine  is 
used  for  power.  The  bucket  has  a  capacity  of  five-eighths  cubic  yard 
and  is  43  inches  wide.  One  man  is  required  to  operate  the  machine 
and  one  man  to  handle  the  track  in  soft  ground.  About  30  gallons 
of  gasoline  or  40  gallons  of  kerosene  are  required  per  10-hour  day. 
The  machine  is  moved  ahead  by  means  of  a  cable  attached  to  a  dead- 
man  or  to  stakes.  The  large  wheels  will  travel  over  fairly  firm  ground 
without  track ;  no  trackman  is  therefore  needed,  except  in  quite  soft 
ground  or  swamp.  The  machine,  complete,  weighs  12  tons.  When 
dismantled  it  can  be  loaded  on  one  flat  car  or  if  transported  by  team 
will  make  12  wagonloads.  The  heaviest  load  is  the  engine,  which 
weighs  5,640  pounds. 

To  assemble  the  machine  takes  five  men  four  or  five  days.  The  same 
number  can  dismantle  it  in  two  days.  The  hoisting  line  is  one-half 
inch  cable  125  to  140  feet  long.  The  loading  line  is  three- fourths 
inch  cable  60  feet  long.  In  single-shift  operation  a  loading  cable  will 
ordinarily  last  10  days  and  a  hoisting  cable  two  weeks.  The  machine 
will  excavate  about  300  cubic  yards  per  shift  or  about  15,000  cubic 
yards  per  month  with  double  shift.  The  maximum  ditch  which  it 
will  dig  at  a  single  cut  has  a  42-foot  top,  12-foot  base,  and  8-foot 
depth.  The  machine  may  be  had  in  widths  of  36  or  40  feet  and  costs 
approximately  $5,500. 

In  enlarging  an  old  ditch  averaging  6  feet  deep  so  as  to  have  a 
channel  13  feet  deep  with  a  10-foot  base,  "a  five-eighths  yard  non- 
rotating  excavator,  with  a  40-foot  boom,  was  used.  The  material  re- 
moved averaged  10  cubic  yards  per  linear  foot.  The  angle  of  swing 
was  75  degrees,  and  the  boom  was  suspended  at  an  angle  of  35°.  A 
direct-line  swing  was  used,  the  swinging  cables  being  attached  di- 
rectly to  the  boom  instead  of  running  through  sheaves  on  the  boom 
and  then  back  to  the  corner  of  the  cross-frame.  This  kind  of  hitch 
gave  a  much  quicker  swing.  A  time  study  made  of  75  dips  gave  the 
following  information :  To  load  the  bucket  took  8  seconds ;  to  hoist, 
swing,  and  dump,  8  seconds;  to  return  the  bucket  to  the  ditch.  8  sec- 
onds ;  the  entire  time  to  complete  one  dip  was,  therefore,  '24  seconds. 
To  move  the  machine  ahead  a  distance  of  9  feet  required  9  seconds. 

Another  type  of  nonrotating  excavator  has  been  developed  which 
has  a  double  boom  with  bull- wheel  swing  instead  of  pivot  swing. 
The  machine  is  made  in  two  sizes,  five-eighths  yard  and  1  yard. 
The  smaller  size  can  be  furnished  with  either  the  caterpillar  mount- 
ing or  the  regular  sliding-track  mounting,  while  the  larger  size  is 
furnished  only  in  the  sliding-track  mounting. 

The  smaller  machine  has  a  five-eighths-yard  bucket,  24-foot  boom, 
and  a  32-horsepower  oil  machine ;  the  machine,  complete,  weighs  32 
tons.  The  track  shoes  are  each  30  feet  long  and  30  inches  wide,  and 


Bui.  300,  U.  S.  Dept.  of  Agriculture. 


PLATE  VII. 


D-3320 

FIG.  I. — CABLE  SWING  DRAG-LINE  EXCAVATOR  WITH  CATERPILLAR  MOUNTING. 


D-3078 
FIG.    2.— NONROTATING    TYPE    OF    DRAG-LINE    EXCAVATOR    WITH    WHEEL 

MOUNTING. 


Bui.  300,  U.  S.  Dept.  of  Agriculture. 


PLATE  VIII. 


D-3308 
FIG.   I. — NONROTATING  SCRAPER  EXCAVATOR  WITH  SLIDING  TRACK  MOUNTING. 


D-3343 


FIG.  2.— WALKING  DRY-LAND  DIPPER  DREDGE. 


EXCAVATING   MACHINERY   USED   IN   LAND   DRAINAGE.  41 

the  spud  feet  are  12  feet  long  by  8  inches  wide.  The  bearing  pres- 
sure when  working  is  about  3  pounds  per  square  inch.  The  distance 
covered  at  each  move  of  the  spud  feet  is  5  to  6  feet,  and  it  requires 
about  30  seconds  to  move  the  machine  ahead  this  distance.  The  road 
speed  is  1J  miles  in  10  hours.  About  30  gallons  of  kerosene  are  re- 
quired per  10-hour  shift.  For  operation  three  men  are  required- 
one  runner,  one  craneman,v  and  one  trackman.  The  machine  can  be 
shipped  on  one  car  and  requires  four  men  one  day  to  assemble  and 
the  same  time  to  dismantle.  The  average  output  is  from  500  to  800 
cubic  yards  in  10  hours.  The  ditch  best  suited  for  the  small  ma- 
chine is  one  with  a  6-foot  top  and  4  feet  of  depth,  although  it  can 
dig  a  ditch  with  a  20-foot  top  and  12  feet  in  depth.  The  machine 
costs  about  $12,000  with  the  sliding-track  mounting  and  $15,000 
with  caterpillar  mounting. 

The  larger  machine  (PL  VIII,  Fig.  1)  has  a  1-yard  bucket,  32-foot 
boom,  and  45-horsepower  engine,  and  weighs,  complete,  45  tons. 
The  track  shoes  are  each  34  feet  long  by  40  inches  wide,  and  the  spud 
feet  2  feet  wide  and  12  feet  long.  The  bearing  pressure  when  work- 
ing is  2.8  pounds  per  square  inch.  The  distance  covered  at  each  move 
of  the  machine  is  5  to  6  feet,  45  seconds  being  required  to  make  the 
move.  The  road  speed  is  about  three- fourths  mile  in  10  hours. 
About  40  gallons  of  kerosene  are  required  per  10-hour  shift.  The 
machine  requires  three  men  for  operation — one  runner,  one  crane- 
man,  and  one  trackman.  Two  cars  are  needed  to  ship  the  machine. 
Four  men  can  assemble  it  in  five  days  and  dismantle  it  in  the  same 
time.  The  average  output  is  from  700  to  1,000  cubic  yards  per  10- 
hour  shift.  The  size  or  ditch  best  suited  for  the  machine  has  a  20- 
foot  top  and  7  feet  in  depth.  It  can,  however,  dig  a  ditch  with  a 
35-foot  top  and  14  feet  deep.  The  machine  costs  about  $18,000. 
Over  dry  earth  roads  four  men  with  four  teams  have  hauled  the 
large  machine  4  miles  in  three  days.  The  smaller  machine  can  be 
shipped  already  assembled,  whereas  the  larger  machine  must  be  dis- 
mantled for  shipping. 

This  type  of  machine  when  digging  does  not  straddle  the  ditch, 
but  works  along  the  center  line  when  a  new  ditch  is  being  dug  or 
on  one  bank  when  an  old  ditch  is  being  enlarged  or  cleaned  out.  No 
earth  "  roll "  is  left  on  the  bank  to  fall  back  into  the  ditch.  On 
these  machines  the  average  life  of  a  loading  line  is  15,000  cubic  yards; 
of  a  hoisting  line,  40,000  cubic  yards ;  of  the  track  lines,  60,000  cubic 
yards.  For  the  larger  machines  the  minimum  economical  project  is 
about  200,000  cubic  yards  with  double-shift  operation.  For  the 
smaller  machines  the  job  should  have  about  30,000  cubic  yards. 
Contractors  state  that  for  the  smaller  machine  they  do  not  want  to 
take  a  job  costing  less  than  $8,000. 


42  BULLETIN   300,    U.    S.    DEPARTMENT   OF   AGRICULTURE. 

ACCESSORY  EQUIPMENT. 

For  housing  men  employed  in  the  operation  of  drag-line  excavators 
many  contractors  use  camp  wagons,  consisting  of  portable  houses 
mounted  on  wagons.  The  most  common  size  is  8  feet  wide  by  18  feet 
long.  The  structure  costs  about  $200  and  a  wagon  with  4-inch 
tires  about  $100. 

SELECTION   OF   SCRAPER   EXCAVATOR. 

In  selecting  a  scraper  excavator,  the  purchaser,  in  addition  to 
choosing  the  most  desirable  kind  of  power  and  the  means  of  moving 


RCACH    Of  BOOM    IN  FCCT  FROM  CENTER  OF BOOM  LUC  AT  VARIOUS  A  HOLES. 
• A ».  To  Tfiit  Dittanct  add  "A"  trhtrt  Distance  from  Cenler  of  Machine  is  required 

-Diagram  of  scraper  excavator  showing  relation  between  the  length  of  boom  and 
the  effective  reach  of  machine. 


over  the  ground  best  suited  to  his  particular  case,  must  determine  the 
length  of  boom  best  suited  to  his  needs. 

Figure  2  is  a  diagram  showing  the  relation  between  the  length  and 
angle  of  elevation  of  the  boom  and  the  effective  reach  of  the  machine. 
In  this  diagram  all  distances  are  referred  to  the  heel  of  the  boom. 
If  it  is  desired  to  refer  horizontal  distances  to  the  center  of  the 
machine,  the  correction  A  must,  of  course,  be  added;  this  distance 
varies  somewhat  with  the  different  makes  of  machine.  The  distance  B 
of  the  heel  of  the  boom  above  the  ground  likewise  varies  slightly  in 
different  machines. 

To  determine  the  maximum  clearance  of  the  bucket  above  the 
ground  for  different  lengths  and  positions  of  boom  the  distance  B 
must  be  added  to  the  vertical  heights  given  on  the  right-hand  margin 
of  the  diagram,  and  from  this  sum  must  be  subtracted  the  distance  C 


EXCAVATING   MACHINERY   USED   IN   LAND   DRAINAGE. 


43 


which  depends  upon  the  kind  of  bucket  used.  Thus  for  a  70-foot 
boom  elevated  at  a-n  angle  of  35  degrees  the  horizontal  distance  from 
the  center  of  the  machine  to  the  bucket  would  be  57+ A,  and  at  that 
position  of  the  boom  the  bucket  would  just  clear  a  waste  bank  of  the 
height  4Q+B-C.  In  using  the  diagram  for  nonrotating  excavators 
the  distance  A  is  not  added,  since  the  boom  of  this  type  of  machine 
swings  at  its  pivot.  Table  17  gives  the  approximate  distances  A  and 
B  in  figure  2  for  the  various  sizes  of  machines  on  the  different  styles 
of  mountings.  The  distances  will  vary  slightly  for  different  makes 
of  excavators. 

TABLE  17. — Limitations  of  operation  of  (Iran-line  excavators. 


SLe  of 
bwkot. 

Length 
of  boom. 

Diameter  of 
turntable. 

Type  of  mounting. 

Distance 
A.i 

Distance 
B.i 

Cu.y.'s. 
i 

Feet. 
30 

Feet.     in. 
4    7 

Caterpillar 

Feet.     in. 
2i-3 

Feet.     in. 
4-41 

1* 

40 

11    3 

Walker  

"  G      4 

3      5 

J 

42 

7 

Caterpillar                                                 

4      3 

5      6 

1 

40 

7 

Skids  and  roller.? 

3      3 

4      5 

14 

45 

9    6 

Caterpillar  

7      5 

9      5 

45 

9    (') 

Skids  and  rollers                                   

7      5 

7      4 

9J 

GO 

14 

Caterpillar 

7      5 

9      5 

2 

60 

14 

Skids  and  rollers  

7      5 

G      5 

2 

50 

15 

do                                                 

9      G 

G      6 

2 

50 

15 

Walker 

10 

4      G 

21 

85 

20 

Skids  and  rollers 

12      2 

7      8 

2V 

85 

20 

Trucks  

12      2 

11      G 

3 

GO 

17 

Walker 

10      8 

4      9 

3 

GO 

17 

Skids  and  rollers 

11      8 

7 

3V 

80 

20 

do                          

12      6 

8 

3* 

100 

24 

do 

12      2 

7    10 

sl 

125 

•  24 

Trucks 

12    10 

13 

4 

80 

24 

Skids  and  roller.;  .  .            

12      6 

8 

4 

100 

24 

do                                                               .     .  . 

15 

8      6 

Bee  figure  2. 


The  clearance  distance  C  (Fig.  2)  varies  with  the  size  of  bucket  and 
size  of  sheaves  used.  Table  18  gives  the  approximate  values  of  C 
for  the  various  sizes  of  bucket'  shown  in  Plate  VII,  Figure  1. 

TABLE  IS. — Clearance  of  buckets  for  draff-line  excavators. 


Size  of 
bucket. 

Distance  C.1 

Size  of 
bucket. 

Distance  C.1 

Cu.  mis. 
1 

Feet. 
12 

Cu.  yds. 

Feet. 
15i  to  16 

I 

124 

3i 

15^  to  16J 

1 

12    to  12!* 

4 

"1 

li 

12i  to  13 

4J 

18J 

2 

14*  to  is 

5 

19    to  23 

2J 

14i  to  15J 

1  See  figure  2. 


The  factor  governing  the  size  of  the  ditch  which  a  certain  machine 
can  dig  is  not  ability  to  excavate,  but,  rather,  to  dispose  of  the  mate- 
rial excavated,  especially  where  the  ditch  is  deep  and  the  yardage 
per  linear  foot  relatively  large.  An  experienced  runner  can  drop 


46  BULLETIN   300,    U.    S.    DEPARTMENT    OF   AGRICULTURE. 

1  to  2  miles  in  10  hours.  It  is  very  useful  on  projects  where  the 
yardage  per  100-foot  station  is  small  and  where  there  are  many  short 
laterals. 

A  dry-land  dipper  dredge  made  of  steel  but  equipped  with  a  dif- 
ferent device  for  walking  than  the  machine  just  described  is  illus- 
trated in  Plate  IX,  Figure  2.  The  machine  when  working  rests 
on  two  skids,  each  3  feet  wide  by  30  feet  long.  The  auxiliary  skids 
each  measure  3  feet  wide  by  28  feet  long.  When  being  moved  the 
weight  of  the  machine  is  shifted  to  the  auxiliary  skids,  and  the  ma- 
chine is  skidded  ahead.  The  auxiliary  skids  are  then  pulled  forward. 
The  machine  will  move  either  forward  or  backward.  It  is  made 
with  various  widths  of  span  from  14  feet  up  to  45  feet  and  in  three 
sizes,  f ,  1,  and  1^  cubic  yards.  The  length  of  boom  varies  for  the 
different  sizes  from  25  feet  to  55  feet. 

A  dry-land  dipper  dredge  which  employs  the  same  method  of 
walking  as  the  machine  illustrated  in  Plate  VIII,  Figure  2,  but  which 
is  equipped  with  a  different  type  of  bucket,  is  used  to  some  extent 
on  drainage  work.  This  machine  (PI.  X,  Fig.  1)  is  built  almost  en- 
tirely of  wood,  longleaf  yellow  pine  being  used,  as  this  wood  has 
greater  resiliency  than  fir.  The  boom  is  of  wood  reinforced  by  truss 
rods.  This  machine  as  ordinarily  built  will  span  a  ditch  with  a  top 
width  of  28  feet.  It  has  a  40-foot  boom  and  a  If-yard  dipper. 
Booms  of  30  or  50  feet  can  be  used.  For  power  a  60-horsepower 
internal-combustion  engine  is  used.  The  dipper  or  scoop  (PL  X, 
Fig.  2)  is  5  feet  wide  at  its  cutting  edge.  By  virtue  of  the  peculiar 
shape  of  the  scoop,  2f  cubic  yards  are  easily  removed  at  each  dip. 

This  excavator  is  mounted  on  six  shoes  or  feet,  one  at  each  corner 
of  the  platform  and  one  on  each  side  of  the  machine  at  the  center. 
The  four  corner  shoes  are  attached  directly  to  the  framework  of  the 
machine  and  move  with  it.  The  machine  moves  by  shifting  its 
weight  to  the  center  feet  and  sliding  forward  on  the  four  corner 
shoes.  The  center  feet  are  then  pulled  forward  by  means  of  chains 
attached  to  a  drum.  The  machine  in  operation  weighs  160  tons,  but 
on  account  of  the  large  bearing  surface  of  the  shoes  the  pressure 
per  square  inch  is  slightly  less  than  10  pounds.  The  front  shoes  are 

6  by  10  feet ;  the  rear  shoes,  6  by  9  feet ;  while  the  middle  shoes  are 

7  by  14  feet;  these  sizes,  of  course,  can  be  varied.    When  operating, 
the  entire  weight  is  on  the  four  corner  shoes. 

To  dismantle  or  assemble  an  old  machine  of  this  type  takes  15  men 
about  30  days.  To  build  an  entirely  new  machine  would  take  the 
same  number  of  men  from  60  to  90  days.  The  machine  can  be 
shipped  on  four  cars. 

For  this  machine  the  minimum  economical  yardage  of  any  one  job 
is  1,000,000  cubic  yards.  The  machine  will  excavate  an  average  of 


EXCAVATING    MACHINERY   USED   IN   LAND   DRAINAGE.  47 

60,000  cubic  yards  a  month  with  double  shift ;  with  steady  running 

it  will  greatly  exceed  this  amount.    Its  operation  requires  4  men 

1  runner,  1  craneman,  1  engineman,  and  1  oiler.  The  runner  handles 
the  hoisting  and  backing  lines,  the  craneman  the  swinging  and  dump- 
ing lines.  The  amount  of  fuel  required  per  shift  is  75  gallons  of 
kerosene  and  1  gallon  of  gasoline.  About  5  gallons  of  cylinder  oil 
are  used  per  24  hours,  or  two  shifts.  The  ditch  for  which  this  ma- 
chine is  best  adapted  is  one  with  a  14-foot  base,  1  to  1  side  slopes, 
and  7  to  8  feet  deep. 

From  a  motion  study  made  of  the  time  of  operation  of  this  ma- 
chine the  average  time  for  50  dips  was  obtained.  To  fill  the  bucket 
required  10  seconds ;  hoisting,  swinging,  and  dumping,  9  seconds ;  re- 
turning to  the  channel  to  dig,  8  seconds ;  entire  time  for  one  complete 
operation,  27  seconds.  Moving  ahead  a  distance  of  6  feet  required 
about  18  seconds. 

THE  DRY-LAND   GRAB-BUCKET   EXCAVATOR. 

Dn-land  grab-bucket  excavators  of  both  the  rotary  and  nonrotat- 
ing  types  are  used  to  some  extent  in  drainage  reclamation.  A  ma- 
chine of  the  former  type  having  an  orange-peel  bucket  is  illustrated 
in  Plate  XI,  Figure  1.  The  excavator  moves  on  skids  and  rollers  or  is 
mounted  on  four  trucks  which  move  on  a  track  built  in  sections  so 
that  it  can  be  taken  up  and  relaid  ahead  of  the  machine  as  the  work 
progresses.  In  the  revolving  type  this  shifting  of  track  is  done  by 
the  machine  itself. 

The  machine  illustrated  is  operating  a  2^-yard  orange-peel  bucket 
on  levee  work.  The  boom  is  90  feet  long.  The  main  engines  are  12 
by  16  inches  and  the  boiler,  vertical  in  type,  74  inches  in  diameter. 
The  track  gauge  of  the  machine  is  26  feet  from  center  to  center;  the 
rotation  speed  is  2  revolutions  per  minute. 

A  type  of  dry-land  grab-bucket  excavator  which  has  been  used  on 
rice  plantations  and  on  marsh  lands  along  the  eastern  coast  for  dig- 
ging ditches  and  building  small  levees  is  shown  in  Plate  XI,  Figure  2. 
This  machine  is  made  in  four  sizes,  with  either  automatic  or  bull- 
wheel  swing.  The  general  dimensions,  weight,  and  price  for  each 
size  of  machine  and  each  type  of  swing  are  given  in  Table  20. 


48 


BULLETIN    300,    U.    S.    DEPARTMENT    OF   AGRICULTURE. 


TABLE    20. — Dimensions    and   costs    of    dry-land    grab-bucket    excavators    icith 
oranye-pcel  bucket  fitted  with  butt-wheel  and  automatic  swing. 


Bucket  capacity. 

9  cubic 

feet. 

15  cubic 
feet. 

21  cubic 
feet. 

1  cubic 
yard. 

Common  dimensions: 
Boom,  length,  feet                          

30 

21    6 
10    0 

15    9 
11    8 
6    0 

10 

9 
28    9 
10,500 
2,300 
,5,470 

8 

26    9 
8,500 
2,200 
$4,  410 
11J 

40 

26    3 
15    0 

17    6 
17    0 

8    0 

20 

11 
38    6 
11,000 
3,950 
$6,  630 
*          18 

10 
36    4 

9,000 
3,750 

$5,  280 
16 

50 

33    5 
18    0 

25    0 
21    0 
10    0 

30 

15 
47    0 
15,000 
7,400 

$8,  760 
27i 

13 
45 
13,000 
7,000 

$7,  480 
26^ 

54 

33    5 
18    0 

25    0 
21    0 
12    0 

40 

15 
52    0 
17,000 
7,  6GO 

$0,725 
31* 

13 

50 
15,  000 
7,200 

$8,  855 
30 

Size  of  platform- 
Length,  feet  and  inches  

Width,  feet  ...              ..           

A  frame- 
Height  above  bottom  of  skids,  feet  and  inches  

Extreme  overall  width  of  machine,  feet  and  inches  
Bull-  wheel  diameter  ,  feet 

Engine,interna  1  combustion  type  with  two  friction  drums, 
tandem  horse  power 

Bull-wheelswing: 
Clearance  under  bucket,  feet  ....        

Radius  of  swing  from  center  of  A  frame,  feet  and  inches  
Weight,  including  drums  and  swinging  gear,  pounds  
Timber  to  build  machine,  feet  b.  m 

Approximate  price  not  including  timber  of  machine  

Tota  1  weight  set  up  for  work,  tons  

Automatic  swing: 
Clearance  under  bucket,  feet  

Radius  of  swing  from  center  of  A  frame,  feet  and  inches  
Weight,  including  drums,  pounds  

Timber  to  build  machine,  feet  b.  m 

Approximate  price,  not  including  timber 

Tota  1  weight  of  machine  set  up  for  work,  tons  .  .     . 

THE  WHEEL  EXCAVATOR. 

There  is  a  type  of  wheel  excavator  which  has  a  steel  frame 
which  supports  on  the  front  end  the  power  equipment  and  on  the 
rear  end  a  pivoted  steel  framework  holding  the  digging  wheel  (PI. 
XII,  Fig.  1).  The  steel  frame  is  mounted  on  two  broad-tired  wheels 
at  the  front  end  and  on  two  apron  tractors  at  the  rear  end.  The 
large  bearing  surface  permits  the  machine  to  operate  in  soft,  swampy 
ground.  The  power  equipment  may  be  either  a  steam  or  an  internal- 
combustion  engine.  The  latter  is  used  the  more  extensively. 

The  excavating  wheel  revolves  upon  antifriction  wheels  placed  just 
outside  its  rim.  The  excavating  scoops  or  buckets  are  placed  on  the 
circumference  of  the  excavating  wheel.  The  front  of  each  scoop  is 
provided  with  a  cutting  edge  which  takes  a  thin  slice  from  the  face 
of  the  trench  as  the  wheel  rotates.  When  the  bucket  reaches  the  top 
of  the  wheel  the  earth  falls  onto  a  belt  conveyor,  which  deposits  it 
on  the  waste  bank  at  one  side  of  the  ditch. 

Table  21  gives  general  data  concerning  each  size  of  machine,  the 
dimensions  of  ditch  each  will  dig,  and  the  approximate  cost  of  the 
various  machines. 


Bui.  300,  U.  S.  Dept.  of  Agriculture. 


PLATE  IX. 


D-26G 


FIG.   I. — DRY-LAND  DIPPER  DREDGE  MOUNTED  ON  TRACK. 


D-4094 

FIG.  2.— WALKING  DRY-LAND  DIPPER  DREDGE  WITH  SKID  WALKING  DEVICE. 


Bui.  300,  U.  S.  Dept.  of  Agriculture. 


PLATE  X. 


D-3074 

FIG.  I. — WALKING  DRY-LAND  DIPPER  DREDGE  WITH  DOUBLE  BOOM  AND 

SCOOP  BUCKET. 


FIG.  2. — SCOOP  BUCKET  OF  DRY-LAND  DREDGE 


Bui.  300,  U.  S.  Dept.  of  Agriculture.' 


PLATE  X!. 


FIG.   I. — DRY-LAND  ROTARY  GRAB-BUCKET  EXCAVATOR. 


FIG.    2. — NONROTATING    DRY-LAND    GRAB-BUCKET    EXCAVATOR. 


Bui.  300,  U.  S.  Dept.  of  Agriculture. 


PLATE  XII, 


FIG.    I. — NONCONVERTIBLE   TYPE    OF    WHEEL    EXCAVATOR. 


FIG.  2.— CONVERTIBLE  TYPE  OF  WHEEL  EXCAVATOR. 


EXCAVATING    MACHINERY   USED   IN    LAND   DRAINAGE. 
TABLE  21. — Data  pertaining  to  the  wheel  excavators. 


49 


Clearance  length  of  machine,  feet. 

.  35 

44 

46 

43 

50 

52 

52 

55 

55 

Clearance  width,  feet  

13i 

4iX3 
10X3i 
30 

27 

3  to  12 
18 

2    6 

3    0 

$7,200 

18 
5X4 
12X5 
40 

36 

4  to  16 
21 

4    6 

3    6 

$8,  300 

21} 

5X4 
12X5J 
50 

45 

4  to  16 
25 

6    0 

4    6 
$10,000 

23| 

6X5 
12X5 
50 

45 

3  to  15 

28 

7    0 

5    2 
$11,500 

25 
6X5 
14X6 
60 

50 

3  to  15 
32 

8    0 

5    6 
$13,  200 

28 
6X5 
14X7 
75 

60 

2  to  12 
38 

9    0 

5    6 
$15,  400 

28 
6X5 
16X7 
80 

70 

2  to  12 
42 

10    0 

5    6 
$16,300 

30 

6X5 
16X7 
90 

80 

2  to  12 
46 

11    0 

5    6 

$17,  100 

32i 
6X5 
16X8 
100 

90 

2  to  12 
50 

12    0 

5    6 
$19,300 

Size  of  front  wheels,  feet  
Size  of  apron  wheels,  feet  
Engine,  horsepower.  ... 

Gasoline  consumption  in  10 
hours,  gallons  

Cutting     speed,     feet     per 
minute  

Weight,  tons            

Top  width  of  ditch,  feet  and 
inches  

Depth    of   ditch,    feet    and 
inches  

Approximate  price     ...  . 

The  road  speed  of  all  sizes  of  the  above  machine  is  about  1  mile 
per  hour.  Two  cars  are  required  for  shipping.  Four  men  can 
unload  and  assemble  one  of  these  machines  in  three  to  five  days. 

There  is  a  wheel  type  of  trench  excavator  so  designed  that  by 
adding  side  knives  a  ditch  Avith  sloping  sides  can  be  dug.  This 
machine  is  illustrated  in  Plate  XII,  Figure  2.  A  series  of  buckets 
attached  to  two  parallel  chains  travel  over  the  circumference  of  a 
wheel  which  is  supported  by  a  central  shaft.  The  cutting  knives 
slice  the  earth  from  the  sides  of  the  ditch,  the  dirt  falling  into  the 
path  of  the  buckets.  The  excavator  is  made  in  two  sizes.  The 
smaller  size  will  dig  a  ditch  5  feet  deep  and  3  feet  in  bottom  width, 
with  side  slopes  1  to  1.  The  larger  size  will  dig  a  ditch  6  feet  deep 
and  5  feet  in  bottom  width,  with  1  to  1  side  slopes.  The  machine  is 
mounted  on  caterpillar  tractors.  For  the  small  size,  4  by  6  foot 
tractors  are  used;  the  large  machine  requires  4J  by  11  foot  tractors. 
Either  steam  or  gasoline  power  is  employed,  the  latter  being  more 
popular.  The  smaller  excavator  weighs  15  tons  and  requires  a  24- 
horsepower  engine ;  the  larger  machine  weighs  20  tons  and  is  oper- 
ated by  a  40-horsepower  engine. 

Both  types  of  wheel  excavators  when  equipped  with  internal- 
combustion  power  require  two  men  to  operate.  If  the  work  is  in 
extremely  soft  ground  two  or  more  additional  men  are  required. 
In  addition  a  team  and  teamster  are  needed  for  hauling  fuel  and 
other  supplies. 

No  average  operation  figures  can  be  given  as  to  the  amount  of 
work  per  shift  that  a  wheel  excavator  will  accomplish,  as  these  vary 
greatly  with  the  character  of  the  soil,  the  conditions  under  which 
the  work  is  being  done,  and  the  operator.  In  one  of  the  Gulf  States 
a  wheel  excavator  equipped  with  a  30-horsepower  gasoline  engine, 
digging  a  ditch  4  feet  deep,  4  feet  wide  at  the  top,  and  2  feet  wide 

93127°— 22 4 


50  BULLETIN    300,    U.    S.    DEPARTMENT    OF   AGRICULTURE. 

at  the  bottom,  made  an  average  distance  of  2,250  linear  feet  in  10 
hours.  The  soil  was  a  hard,  yellow,  sandy  clay,  overlain  by  a  tnrfy 
muck  varying  in  depth  up  to  2J  feet.  The  total  length  of  ditches 
dug  was  165  miles,  two  machines  of  the  same  size  being  used.  The 
maximum  distance  dug  in  10  hours  was  6,600  feet.  The  fuel  con- 
sumption per  shift  of  10  hours  was  50  gallons  of  gasoline. 

On  another  project  a  wheel  machine  of  the  same  size  was  used. 
The  soil  was  a  silt  loam,  firm  and  uniform,  but  not  tenacious.  The 
average  length  of  ditch  cut  per  day  was  800  feet,  while  the  maximum 
was  1,950  feet.  The  total  length  of  ditch  cut  was  117,000  feet. 

Wheel  excavators  are  adapted  to  the  excavation  of  ditches  in  soils 
free  from  stumps,  buried  timbers,  bowlders,  or  rock.  They  have 
been  used  extensively  in  the  Gulf  States  on  flat,  swampy  prairie 

lands. 

THE  HYDRAULIC  DREDGE. 

The  hydraulic  dredge  has  been  used  only  to  a  limited  extent  in 
the  construction  of  drainage  ditches,  due  to  the  fact  that  nearly 
all  such  ditches  are  too  small  to  be  dug  economically  by  this  method. 
Hydraulic  dredges  are  suitable  for  digging  ditches  800  or  more 
square  feet  in  cross  section,  for  building  levees  under  favorable  con- 
ditions, and  especially  for  building  up  tidal  flats  and  lowlands. 

The  principal  parts  of  the  hydraulic  dredge  are  a  centrifugal 
pump,  the  power  machinery  to  drive  the  pump,  and  the  hull  on 
which  the  machinery  is  mounted.  When  the  dredge  is  operating 
the  material  to  be  excavated,  mixed  with  water,  is  drawn  in  through 
the  suction  pipe  and  discharged  where  desired  through  a  line  of 
pipe  sometimes  several  thousand  feet  long.  Coarse  sand,  gravel, 
muck,  and  silt  are  easily  handled  in  this  way,  and  by  the  use  of  a 
rotary  cutter  on  the  end  of  the  suction  pipe  comparatively  hard 
clay  can  be  removed.  The  machine  does  not  work  well  where  there 
are  stumps,  logs,  large  stones,  or  other  such  obstructions. 

The  dredge  must  be  moved  frequently.  This  is  usually  accom- 
plished by  cables  operated  by  a  hoisting  engine  and  attached  to 
deadmen  on  the  shore  or,  if  working  in  a  large  stream,  to  anchors 
dropped  into  the  stream.  Either  one  or  two  spuds  are  arranged  at 
the  stern  of  the  dredge,  which  hold  that  end  of  the  hull  in  position. 
By  swinging  the  head  of  the  dredge  the  amount  of  material  de- 
livered to  the  pump  can  be  regulated  so  that  the  dredge  will  handle 
the  maximum  percentage  of  solids. 

To  determine  whether  the  dredge  is  working  properly  a  vacuum 
gauge  is  attached  to  the  suction  pipe  and  a  pressure  gauge  to  the 
discharge  pipe.  The  operator  by  means  of  the  vacuum  gauge  can 
tell  when  the  pump  is  handling  the  proper  amount  of  material,  as 


EXCAVATING   MACHINERY   USED   IN   LAND   DRAINAGE.  51 

the  reading  on  the  gauge  is  greater  when  pumping  solid  material 
than  when  pumping  water  only.  The  reading  on  the  pressure 
gauge  varies  with  the  length  of  the  discharge  pipe  used  and  with 
the  elevation  to  which  the  material  is  pumped.  An  experienced 
operator,  however,  can  tell  when  the  operations  are  being  carried  on 
properly.  The  reading  in  inches  on  the  vacuum  gauge  can  be 
reduced  to  the  equivalent  head  in  feet  by  multiplying  the  number 
of  inches  by  1.13.  The  reading  on  the  pressure  gauge,  in  pounds 
per  square  inch,  can  be  reduced  to  the  equivalent  head  in  feet  by 
multiplying  the  gauge  reading  in  pounds  by  2.30.  The  practical 
maximum  discharge  pressure  is  from  45  to  55  pounds,  depending 
somewrhat  upon  the  size  of  the  pump.  For  extra  high  heads,  relay 
or  booster  pumps  are  used ;  that  is,  the  first  pump  delivers  the  ma- 
terial through  a  certain  length  of  discharge  pipe  into  the  suction 
line  of  the  relay  pump.  An  auxiliary  pump  is  often  used  to  dis- 
charge water  continuously  into  the  shell  of  the  dredging  pump  to 
aid  in  moving  the  material  pumped.  , 

The  suction  head  is  the  distance  from  the  surface  of  the  water  to 
the  center  of  the  pump  plus  pipe  friction  and  losses  of  head  through 
the  rotary  cutter  and  at  the  entrance  of  the  suction  pipe.  The  total 
suction  head  should  not  ordinarily  exceed  25  feet,  a  condition  easily 
met  by  the  hydraulic  dredge.  The  discharge  head  is  the  difference 
in  level  between  the  pump  shaft  and  the  point  of  discharge,  plus 
the  friction  in  the  discharge  pipe. 

For  priming  the  pump  a  small  centrifugal  pump  is  commonly 
used.  The  method  is  to  raise  the  suction  pipe  until  its  end  is  higher 
than  the  dredging  pump  and  prime  until  priming  water  discharges 
from  the  suction  pipe;  the  suction  pipe  is  then  dropped  into  the 
water  and  the  dredge  pump  started. 

SELECTION  OF  EQUIPMENT. 

In  order  to  select  the  proper  equipment  several  ruling  factors 
must  be  considered.  The  character  of  the  material  to  be  excavated, 
the  maximum  depth  of  water  from  which  the  material  is  taken,  the 
maximum  elevation  at  which  the  material  is  to  be  deposited,  and  the 
maximum  and  minimum  length  of  discharge  pipe  to  be  used,  are 
conditions  which  must  first  be  determined.  Likewise  the  quantity 
of  material  to  be  excavated  per  shift  must  be  decided  upon,  as  well 
as  the  type  of  power  equipment  and  method  of  drive. 

The  percentage  of  solids  moved  depends  upon  the  character  of 
material  pumped  and  the  velocity  in  the  discharge  pipe.  In  mud 
or  silt  20  per  cent  or  more  solid  material  may  be  handled  with  the 
water ;  in  sand  and  gravel  probably  not  more  than  10  per  cent.  Light 


52  BULLETIN   300,    U.    S.    DEPARTMENT   OF   AGRICULTURE. 

silt  or  fine  sand  are  easily  carried  in  suspension,  and  for  these  a 
larger  diameter  of  discharge  pipe  with  a  lower  velocity  may  be  used 
than  for  coarse  sand  and  gravel.  The  maximum  velocity  of  dis- 
charge is  reached  when  the  friction  head  begins  to  increase  too 
rapidly.  The  velocity  at  which  the  abrasive  action  on  the  internal 
surface  of  the  discharge  pipe  begins  to  be  serious  occurs  at  about 
12  feet  per  second  for  pipes  20  inches  in  diameter.  The  gain  in  the 
proportion  of  solids  transported  at  high  velocity  may  be  offset  by 
the  cost  of  more  frequent  renewals  of  discharge  pipe.  Discharge 
pipes  having  a  diameter  of  15  inches  and  a  thickness  of  wall  of 
eleven-sixty-fourths  inch,  and  containing  from  0.5  to  0.6  per  cent  of 
carbon  and  from  0.6  to  0.7  per  cent  of  manganese,  have  passed  more 
than  300,000  cubic  yards  without  wearing  out.  Since  the  wear  is 
chiefly  along  its  bottom,  the  pipe  may  be  marked  and  rotated  a 
quarter  turn  occasionally  to  insure  even  wear. 

The  smaller  the  diameter  of  the  discharge  pipe  the  higher  the 
velocity  for  a  given  discharge,  and  the  greater  the  percentage  of 
solids  which  will  be  transported.  The  larger  the  discharge  pipe 
the  greater  the  volume  of  mixture  carried  for  a  given  amount  of 
power.  The  amount  of  power  must  be  determined  that  will  give 
sufficient  velocity  to  carry  the  material  in  suspension  and  deliver  the 
maximum  amount  of  solids.  With  6-inch  pipe  or  less,  sand  mix- 
tures will  flow  well  with  a  pipe  velocity  of  5  feet  per  second.  In 
a  20-inch  pipe  it  has  been  found  that  a  velocity  of  10  feet  per  second 
will  transport  sand. 

The  smaller  pumps,  12  inches  and  under,  may  be  either  belt-driven 
or  direct-connected  to  the  power  unit.  The  larger  pumps  are  usually 
direct-connected  to  the  power  unit,  this  method  of  drive  being  the 
most  economical.  When  there  happens  to  be  great  variation  in  the 
length  of  discharge  pipe  it  is  advisable  to  have  impellers  of  differ- 
ent diameters — one  of  large  diameter  when  long  discharge  pipes 
are  used  and  a  smaller  impeller  with  a  short  discharge  pipe.  By 
using  the  proper  size  of  impeller  the  engine  is  better  able  to  main- 
tain its  normal  speed. 

DETERMINATION   OF   SIZE   OF  PLANT. 

To  determine  the  amount  of  power  required  to  operate  the  pump 
the  following  factors  must  be  considered:  (1)  diameter  of  suction 
and  discharge  pipe;  (2)  kinds  of  pipe  and  length  of  each  kind;  (3) 
character  of  end  connections ;  (4)  static  head;  (5)  efficiency  of  pump 
and  engine  (which  may  vary  from  30  to  70  per  cent)  ;  and  (6)  nature 
of  material  and  percentage  of  solids  transported. 


EXCAVATING    MACHINERY   USED   IN   LAND   DRAINAGE. 


53 


The  required  horsepower  of  the  engine  may  be  obtained  by  multi- 
plying the  weight  of  the  mixture  transported  by  the  total  head  in 
feet,  and  .a  coefficient  dependent  upon  the  combined  efficiencies  of  the 
pump  and  engine.  Efficiencies  over  50  per  cent  are  rarely  obtained 
in  a  hydraulic  dredge  pump.  Table  22,  compiled  from  data  pub- 
lished by  manufacturers  of  hydraulic  dredges,  gives  the  capacities 
and  required  power  for  pumps  of  various  sizes. 

TABLE  22. — Capacities  and  required  poiver  of  hydraulic  dredges. 


Solids  pumped  per  hour. 

Approxi- 

Diameter 

mate 

of 

horse- 

suction 
and 
discharge 
pipes. 

Normal 
capacity. 

10 
per  cent. 

15 
per  cent. 

20 
per  cent. 

power 
required 
for  each 
foot  of 

head. 

Gallons 

per 

Cubic 

Cubic 

Cubic 

Inches. 

minute. 

yards. 

yards. 

yards. 

4 

450 

12 

18 

24 

0.4 

5 

700 

20 

30 

40 

.6 

6 

1,000 

30 

45 

60 

.8 

8 

1,800 

50 

75 

100 

1.5 

10 

2,800 

90 

135 

180 

2.5 

12 

4,000 

130 

195 

260 

3.0 

15 

6,300 

200 

300 

400 

5.0 

18 

9,000 

300 

450 

600 

7.0 

20 

13,  000 

375 

560 

750 

8.0 

24 

17,000 

500 

750 

1,000 

10.0 

Suppose  it  is  desired  to  select  pump  and  power  equipment  for  a 
hydraulic  dredge  to  be  used  in  building  a  levee  with  a  top  elevation 
20  feet  above  the  water  surface,  the  maximum  length  of  discharge 
pipe  to  be  2,000  feet,  the  material  to  be  pumped  being  sand  which  it 
is  desired  to  pump  at  the  rate  of  130  cubic  yards  of  solids  per  hour. 
In  pumping  sand  it  is  assumed  that  10  per  cent  of  the  discharge  is 
solids.  Table  22  shows  that  a  12-inch  pump  will  deliver  the  required 
amount  of  material. 

To  determine  the  size  of  the  power  unit  to  work  the  pump  effi- 
ciently it  is  necessary  to  determine  the  head  against  which  the  pump 
is  to  operate.  This  includes  static  head,  entrance  loss,  and  friction  in 
suction  and  discharge  pipes.  Table  23  shows  the  velocity  of  flow 
and  friction  head  per  100  feet  for  water  in  clean  iron  pipe,  as  given 
by  pump  manufacturers.  To  obtain  the  friction  head  for  the  mix- 
ture pumped  by  a  hydraulic  dredge,  the  figures  given  in  Table  23 
should  be  increased  from  40  to  75  per  cent,  depending  upon  the 
character  of  the  material  pumped. 


54 


BULLETIN   300,   U.   S.   DEPARTMENT  OF  AGRICULTURE. 


TABLE  23. — Friction  head  per  100  feet  and  velocity  of  flow  of  water  in  clean  iron 

pipe. 


Gal- 
lons 
per 
min- 
ute. 

Inside  diameter  of  pipe  in  inches. 

4 

5 

6 

8 

10 

12 

14 

15 

18 

20 

22 

24 

450 
750 
1,000 
1,800 
2,500 
3,000 
4,000 
6,000 
7,500 
10,000 
12,500 
14,000 
17,000 

Friction  head,  feet. 
Velocity,  feet  per 
second. 
Friction  head,  feet. 
Velocity,  feet  per 
second. 
Friction  head,  feet. 
Velocity,  feet  per 
second. 
Friction  head  feet 

13.9 
11.4 

*4.6 
7.3 

11.3 
12.2 

1.9 
5.1 

5.1 

8.4 

9.0 
11.3 

1.2 

4.8 

2.2 
6.4 

0.74 
4.0 

6.92 
11.5 

13.3 

15.9 

2.3 
7.4 

4.39 
10.2 

6.3 
12.2 

0.94 
5.1 

1.78 
7.09 

2.55 

8.5 

4.65 
11.5 

Velocity,  feet  per 
second. 
Friction  head  feet 

0.84 
5.2 

1.19 
6.3 

2.10 
8.9 

4.8 
13.4 

Velocity,  feet  per 
second. 
Friction  head,  feet. 
Velocity,  feet  per 
second. 
Friction  head  feet 

1.45 

7.2 

2.9 
10.8 

4  4 

Velocity,  feet  per 
second. 
Friction  head,  feet. 
Velocity,  feet  per 
second. 
Friction  head,  feet 

1.43 

8.2 

2  18 

1  30 

Velocity,  feet  per 
second. 
Friction  head,  feet. 
Velocity,  feet  per 
second. 
|  Friction  head  feet 

13.5 

10.3 

3.67 
13.7 

8.26 

2.25 
11.0 

3.06 
13.0 

4.25 
15  4 

1.39 
9.0 

1.87 
10.5 

2.  04 
12  6 



1.25 
9.0 

1.79 
10.79 

2..6 
13.1 

Velocity,  feet  per 
second. 
(Friction  head,  feet. 
Velocity,  feet  per 
second. 
Friction  head  feet 

3.8 
15.3 

Velocity,  feet  per 
second. 

The  loss  of  head  due  to  an  elbow  in  a  12-inch  pipe  line  may  be  esti- 
mated at  2  feet.  The  entrance  loss  is  usually  considered  equivalent 
to  2  or  3  feet  of  head.  The  minimum  velocity  that  will  transport 
sand  in  a  12-inch  pipe  has  been  found  by  experience  to  be  approxi- 
mately 8  feet  per  second.  Table  23  shows  that  for  clear  water  the 
friction  loss  per  100  feet  of  12-inch  and  14-inch  pipe  is  4.65  feet  and 
2.10  feet,  respectively,  and  that  the  velocity  of  flow  is  11.5  and  8.9 
feet  per  second,  respectively.  As  the  velocity  in  the  14-inch  pipe  is 
sufficient  to  transport  the  10  per  cent  mixture  to  be  pumped,  this  size 
of  pipe  should  be  used,  because  there  is  less  friction  than  with  the 
12-inch  pipe. 

The  2,000  feet  of  discharge  pipe  would  therefore  develop  a  friction 
head  of  20  by  2.10  feet,  or  42  feet,  with  clear  water ;  with  a  10  per  cent 
sand  mixture  this  head  should  be  increased  at  least  50  per  cent,  or  to 
63  feet. 


EXCAVATING   MACHINERY   USED   IN   LAND   DRAINAGE  55 

If  the  pipe  lines  make  four  elbow  turns  and  the  friction  loss  in  the 
suction  pipe,  which  is  seldom  more  than  25  to  40  feet  long,  is  omitted, 
the  total  head  to  be  pumped  against  is  as  follows : 

Feet. 

Static  head  (difference  in  elevation  of  water  surface  and  top  of  levee) 20 

Friction  loss  in  2,000  feet  of  14-inch  discharge  pipe ^ C3 

Loss  of  head  in  4  elbow  turns 8 

Entrance  loss 2 

Total  head  to  be  pumped  against 93 

Table  22  shows  that  approximately  3  horsepower  is  required  for 
each  foot  of  head  to  make  a  12-inch  centrifugal  pump  deliver  130 
cubic  yards  of  solids  per  hour  in  a  10  per.  cent  mixture.  It  would, 
therefore,  be  necessary  to  have  279  horsepower  available  to  pump 
against  the  required  head  of  93  feet.  As  it  is  advisable  to  have  ample 
power  available,  a  300  or  preferably  a  350  horsepower  engine  should 
be  used.  If  electric  power  is  used,  a  400-horsepower  motor  should  be 
installed,  as  electric  equipment  can  not  successfully  be  subjected  to 
overload  as  can  steam  equipment. 

In  determining  the  size  of  plant  required  it  is  important  to  provide 
ample  reserve  power  and  capacity.  This  is  necessary  because  of  the 
many  variable  and  unknown  factors  entering  into  the  operation  of 
hydraulic  dredges.  A  choked  suction  pipe,  pump,  or  discharge  pipe 
can  frequently  be  corrected  without  serious  loss  of  time  if  ample 
reserve  power  is  available. 

OUTPUT. 

The  amount  of  material  pumped  in  a  unit  of  time  and  the  fuel 
consumption  per  cubic  yard  pumped  vary,  of  course,  with  the  kind 
of  material  pumped  and  the  conditions  under  which  operations  are 
conducted.  The  information  given  in  Table  24  is  representative  of 
this  type  of  dredge. 

In  the  operation  of  hydraulic  dredges  there  is  considerable  lost 
time,  due  to  delays  caused  by  such  items  as  changes  in  discharge  pipe, 
choked  suction  pipe,  pump,  or  discharge  pipe,  repairs,  and  renewals. 
Not  more  than  50  to  75  per  cent  of  the  time  will  be  spent  in  actual 
operation. 


56  BULLETIN    300,    U.    S.    DEPARTMENT   OF   AGRICULTURE. 

TABLE  24. — Operating  data  for  United  States  liydmiilie  dredges? 


Diameter 
of  dis- 
charge 
pipe. 

» 
Material. 

Average 
gauge 
pressure 
in  dis- 
charge 
pipe. 

Average 
vacuum 
in  suc- 
tion pipe. 

Total 
head. 

Average 
output 
per  hour 
of  pump- 
ing. 

Coal 
used  per 
cubic 
yard 
pumped. 

Total 
excavation. 

Inches. 
10 

Sand                              

Pounds 
per  square 
inch. 
14 

Inches. 
15 

Feet. 

49 

Cubic 
yards. 
89 

Pounds. 
13.3 

Cubic  yards. 
163  288 

12 

9 

20 

43 

97 

15  63 

9  172 

12 

Sand  ,  gravel  ,  shells     

18 

10 

53 

199 

6.5 

16,  889 

12 

Sand 

18 

12 

55 

107 

6.35 

55  131 

12 

Sand  and  gravel  

14 

9.7 

42 

76 

14.4 

123,  959 

12 

do 

10 

14 

39 

105 

12.6 

165  028 

12 

Mud.           

16 

15 

54 

181 

4.22 

376,  079 

15 

*  Mud,  clay,  sand  

12.6 

16.9 

48 

141 

9.8 

230,  257 

15 

Gravel  and  sand 

12 

20 

50 

257 

6  79 

310  370 

15 

Silt,  clay,  and  sand  

22 

18 

71 

172 

8.64 

488,  875 

15 

Mud  and  silt 

18 

12 

55 

293 

3.2 

792  807 

15 

Mud,  clay,  and  sand  

3.5 

11 

21 

309 

2.71 

1,  078,  2S5 

15 

Sand,  mud,  and  shells 

16 

7 

45 

551 

3.35 

1.  298,  597 

18 

Sand  and  mud 

14 

18 

53 

113 

15 

228  263 

18 
20 

Sand  and  mud,  some  rock  
Sand  and  rock  

22 
15.4 

9 
16 

61 
54 

286 
336 

6.7 
5.27 

1,  045,  689 
365,  433 

20 

Mud,  sand,  and  shell  

28 

14 

80 

1.130 

4.31 

444,  665 

20 
20 

Sand,  mud,  and  stiff  clay  
Mud  and  clay  

25 

28 

12 

18 

71 

85 

180 
685 

8.41 
2.45 

527,  360 
636,  417 

20 

Mud  snd  sand 

32 

12 

87 

503 

7.33 

1,270,703 

20 

Mud  and  clay  

21 

15 

65 

827 

2.48 

1,  341,  835 

20 

Silt,  quicksand 

32 

12 

87 

369 

3.75 

1,  687,  476 

20 

Mud,  sand,  clay 

26 

g 

69 

1  016 

3.07 

3  697  875 

24 

Sand  and  gravel 

9 

13.5 

36 

542 

10.4 

59,  702 

1  Annual  Report,  Chief  of  Engineers,  United  States  Army,  Floating  Plant  (1915). 
USE  IN   LEVEE   CONSTRUCTION. 

The  hydraulic  dredge  can  be  used  successfully  in  constructing 
levees  where  water  and  soil  conditions  are  suitable  and  where  there 
is  sufficient  yardage  to  pay  for  the  installation  of  such  a  machine. 
Suitable  soils  are  those  largely  composed  of  sand  with  some  silt  or 
clay.  If  a  large  amount  of  silt  or  clay  is  present  there  is  a  tendency 
for  the  material  to  remain  in  suspension  for  considerable  time  and 
it  is  difficult  to  form  the  levee.  Plate  XIII,  Figure  1,  illustrates  the 
method  of  forming  the  desired  slopes  by  means  of  steel  boards. 
These  boards,  made  of  No.  14  gauge  steel,  about  18  inches  wide  and 
10  feet  long,  with  angle-iron  top,  are  light  enough  to  be  easily  moved 
by  .one  man.  They  may  be  placed  in  a  continuous  single  line  along 
the  intersection  of  the  side  slope  with  the  natural  slope  at  the  end  of 
the  fill,  or  they  may  be  placed  in  a  staggered  line  along  the  slope  as 
shown.  Several  men  equipped  with  shovels  are  necessary  to  dis- 
tribute the  material  evenly  and  to  move  the  slope  boards  ahead  as  the 
levee  is  built  up. 

A  hydraulic  dredge  (PI.  XIII,  Fig.  2)  with  hull  90  by  24  by  5J 
feet,  having  a  centrifugal  pump  with  12-inch  suction  pipe,  14-inch 
discharge  pipe,  a  250-hersepower  tandem  compound  engine,  and  a 
locomotive-type  boiler  nominally  rated  at  150  horsepower,  was  used 
in  constructing  a  section  of  levee  along  the  Mississippi  River  near 


Bui.  300,  U.  S.  Dept.  of  Agriculture. 


PLATE  XIII. 


D-3079 

FIG.    I. — BUILDING  A   LEVEE  BY   MEANS  OF  STAGGERED  SLOPE  BOARDS. 


D-3080 


FIG.  2. — HYDRAULIC  DREDGE  BUILDING  LEVEE. 


\ 


D-3077 


FIG.  3.— A  TYPE  OF  CUTTER  HEAD  USED  ON  THE  HYDRAULIC  DREDGE. 


Bui.  300,  U.  S.  Dept.  of  Agriculture. 


PLATE  XIV. 


FIG.    I. — DISCHARGE   PIPE  OF   HYDRAULIC   DREDGE  SHOWING   MATERIAL 
PASSING  THROUGH  OPENINGS  IN  BOTTOM  OF  PIPE. 


FIG.  2. — DISCHARGE  PIPE  OPENING  WITH  SHUTTER. 


FIG.  3.— RELEASE  VALVE  IN  DISCHARGE  PIPE. 


EXCAVATING    MACHINERY   USED   IN   LAND   DRAINAGE,  57 

Muscatine,  Iowa.  The  material  was  sufficiently  hard  to  require  a 
cutter  head  (PL  XIII,  Fig.  3).  The  mechanism  for  running  the 
cutter  head  was  operated  by  a  vertical  two-cylinder  steam  engine. 
For  moving  the  dredge  a  6  by  9^  inch  double-cylinder,  three-drum 
hoisting  engine  was  used,  the  cable  being  secured  to  a  deadman  on 
the  shore  at  one  end  and  to  a  heavy  anchor  in  the  river  at  the  other. 
One  drum  was  used  to  raise  and  lower  the  suction  pipe.  The  hoist- 
ing engine  used  steam  from  the  main  boiler.  For  operating  the 
pump  a  rope  drive  was  used,  the  rope  being  four-strand  and  1J 
inches  in  diameter.  Rope  transmission  is  believed  to  be  less  affected 
by  moisture  than  leather  belting;  moreover,  there  is  less  slippage 
with  rope  drive. 

The  discharge  pipe  was  carried  from  the  dredge  to  the  shore  on 
barges,  each  40  by  14  by  2  feet.  The  material  was  deposited  on  the 
levee  through  4  by  6  inch  openings  in  the  bottom  of  the  discharge 
pipe  (PL  XIV,  Fig.  1).  The  openings  were  equipped  with  shutters 
(PL  XIV,  Fig.  2),  so  they  could  be  opened  or  closed  as  desired.  The 
discharge  pipe  was  divided  into  25-foot  lengths,  each  of  the  last 
10  lengths  being  equipped  with  three  openings  or  gates.  The  pump 
became  clogged  occasionally  with  masses  of  roots,  and  to  prevent 
damage  to  the  discharge  pipe  from  the  resuction  in  the  pump  a  joint 
of  pipe  having  a  release  valve  which  allowed  air  to  enter  (PL  XIV, 
Fig.  3)  was  inserted  in  the  pipe.  Resuction  will  cause  a  14-inch  dis- 
charge pipe  of  14-gauge  material  to  collapse  unless  release  valves 
are  provided.  The  pump  was  equipped  with  pressure  and  vacuum 
gauges  to  enable  the  operator  to  gauge  the  working  of  the  dredge. 

The  operating  crew  for  one  shift  consisted  of  a  foreman,  an  op- 
erator, a  fireman,  and  a  deck  hand.  From  5  to  10  men  were  required 
at  the  end  of  the  discharge  pipe,  depending  upon  whether  an  old 
levee  was  being  enlarged  or  a  new  levee  built.  The  coal  consumption 
averaged  from  4  to  5  tons  per  11-hour  shift.  When  the  condenser 
was  not  used  about  three-fourths  ton  more  fuel  per  shift  was  needed. 
With  steady  running  the  dredge  pumped  from  2,000  to  2,400  cubic 
yards  in  11  hours;  on  the  job  as  a  whole,  however,  the  average  was 
from  1,000  to  1,200  cubic  yards  per  shift. 

The  open  type  of  impeller  with  five  blades  was  used  on  the  dredge 
described.  This  impeller  has  adjustable  shoes  which  can  be  replaced 
when  worn. 

To  build  a  hull  for  a  dredge  of  this  description  takes  8  men  6 
weeks;  to  assemble  the  machinery,  6  men  about  6  weeks;  to  build  a 
coal  barge  75  by  16  by  5  feet,  and  5  pontoons,  each  40  by  14  by  2  feet, 
will  take  8  men  G  weeks.  The  cost  of  the  dredge  complete  is  about 
$30,000,  including  barges  and  pipe. 

In  excavation  where  many  roots  are  encountered,  it  has  been  found 
that  the  inclosed  impeller  having  two  blades  works  exceptionally 


Pamphlet 

Binder 
Gaylord  Bros. 

Makers 
Syracuse,  N.  Y. 

PAT.  JAN  21,  1908 


4933-li 

TA  T3 

Y5 


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